Various micro-optimizations

ImperatorToCK3/CK3/CK3LocDB.cs

@@ -6,7 +6,7 @@
 using Murmur;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
+using ZLinq;
 
 namespace ImperatorToCK3.CK3;
 
@@ -23,7 +23,7 @@
 		modFSLocDB.ScrapeLocalizations(ck3ModFS);
 		ImportLocFromLocDB(modFSLocDB);
 
-		// Read loc from ImperatorToCK3 congifurables.
+		// Read loc from ImperatorToCK3 configurables.
 		// It will only be outputted for keys localized in neither ModFSLocDB nor ConverterGeneratedLocDB.
 		LoadOptionalLoc(activeModFlags);
 	}
@@ -54,7 +54,8 @@
 			if (!Directory.Exists(modLocDir)) {
 				continue;
 			}
-			optionalLocFilePaths = optionalLocFilePaths.Concat(Directory.GetFiles(modLocDir, "*.yml", SearchOption.AllDirectories)).ToArray();
+			optionalLocFilePaths = optionalLocFilePaths.AsValueEnumerable()
+				.Concat(Directory.GetFiles(modLocDir, "*.yml", SearchOption.AllDirectories)).ToArray();
 		}
 
 		var optionalConverterLocDB = new LocDB(ConverterGlobals.PrimaryLanguage, ConverterGlobals.SecondaryLanguages);
@@ -99,7 +100,7 @@
 		}
 	}
 
 	// TODO: add unit test for combining loc from all the sources into one locblock
 
 
 	public CK3LocBlock? GetLocBlockForKey(string key) {
@@ -161,7 +162,13 @@
 	private static string GetHashStrForKey(string key) {
 		var keyBytes = System.Text.Encoding.UTF8.GetBytes(key);
 		var hash = murmur3A.ComputeHash(keyBytes);
-		return string.Concat(hash.Select(b => b.ToString("X2")));
+
+		var sb = new System.Text.StringBuilder(hash.Length * 2);
+		foreach (byte t in hash) {
+			sb.Append(t.ToString("X2"));
+		}
+
+		return sb.ToString();
 	}
 
 	private readonly Dictionary<string, string> hashToKeyDict = []; // stores MurmurHash3A hash to key mapping

ImperatorToCK3/CK3/Characters/Character.cs

@@ -17,11 +17,10 @@
 using ImperatorToCK3.Mappers.UnitType;
 using Open.Collections;
 using System.Collections.Generic;
-using System.Collections.Immutable;
-using System.Linq;
 using System.Text;
+using ZLinq;
 
-namespace ImperatorToCK3.CK3.Characters; 
+namespace ImperatorToCK3.CK3.Characters;
 
 internal sealed class Character : IIdentifiable<string> {
 	public string Id { get; }
@@ -37,7 +36,7 @@
 				return false;
 			}
 
-			var value = entries.LastOrDefault().Value;
+			var value = entries.AsValueEnumerable().LastOrDefault().Value;
 			if (value is string str) {
 				return str == "yes";
 			}
@@ -66,11 +65,12 @@
 	public string? GetNickname(Date date) {
 		return History.GetFieldValue("give_nickname", date)?.ToString();
 	}
-	
-	public IEnumerable<string> BaseTraits => History.Fields["traits"].InitialEntries
+
+	public List<string> BaseTraits => History.Fields["traits"].InitialEntries.AsValueEnumerable()
 		.Where(kvp => kvp.Key == "trait")
 		.Select(kvp => kvp.Value)
-		.Cast<string>();
+		.Cast<string>()
+		.ToList();
 
 	public void AddBaseTrait(string traitId) {
 		History.Fields["traits"].InitialEntries.Add(new KeyValuePair<string, object>("trait", traitId));
@@ -94,7 +94,7 @@
 	}
 
 	public Date BirthDate {
-		get => History.Fields["birth"].DateToEntriesDict.First().Key;
+		get => History.Fields["birth"].DateToEntriesDict.AsValueEnumerable().First().Key;
 		set {
 			var field = History.Fields["birth"];
 			field.RemoveAllEntries();
@@ -105,7 +105,7 @@
 	public Date? DeathDate {
 		get {
 			var entriesDict = History.Fields["death"].DateToEntriesDict;
-			return entriesDict.Count == 0 ? null : entriesDict.First().Key;
+			return entriesDict.Count == 0 ? null : entriesDict.AsValueEnumerable().First().Key;
 		}
 		set {
 			var field = History.Fields["death"];
@@ -121,7 +121,7 @@
 			if (entriesDict.Count == 0) {
 				return null;
 			}
-			var deathObj = entriesDict.First().Value[^1].Value;
+			var deathObj = entriesDict.AsValueEnumerable().First().Value[^1].Value;
 			if (deathObj is not StringOfItem deathStrOfItem || !deathStrOfItem.IsArrayOrObject()) {
 				return null;
 			}
@@ -142,7 +142,7 @@
 			}
 
 			// Modify the last entry in the history to include the death reason.
-			var entriesList = entriesDict.First().Value;
+			var entriesList = entriesDict.AsValueEnumerable().First().Value;
 			var lastEntry = entriesList[^1];
 			// No reason provided.
 			var deathStr = value is null ? "yes" : $"{{ death_reason = {value} }}";
@@ -226,7 +226,7 @@
 
 	public void InitSpousesCache() {
 		var spousesHistoryField = History.Fields["spouses"];
-		foreach (var spouseId in spousesHistoryField.InitialEntries.Select(kvp => kvp.Value.ToString())) {
+		foreach (var spouseId in spousesHistoryField.InitialEntries.AsValueEnumerable().Select(kvp => kvp.Value.ToString())) {
 			if (spouseId is null) {
 				continue;
 			}
@@ -251,7 +251,7 @@
 
 	public void InitConcubinesCache() {
 		var concubinesHistoryField = History.Fields["concubines"];
-		foreach (var concubineId in concubinesHistoryField.InitialEntries.Select(kvp => kvp.Value.ToString())) {
+		foreach (var concubineId in concubinesHistoryField.InitialEntries.AsValueEnumerable().Select(kvp => kvp.Value.ToString())) {
 			if (concubineId is null) {
 				continue;
 			}
@@ -287,246 +287,246 @@
 		SetName(name, null);
 		BirthDate = birthDate;
 	}
 	public Character(
 		RulerTerm.PreImperatorRulerInfo preImperatorRuler,
 		Date rulerTermStart,
 		Country imperatorCountry,
 		CharacterCollection characters,
 		LocDB irLocDB,
 		CK3LocDB ck3LocDB,
 		ReligionMapper religionMapper,
 		CultureMapper cultureMapper,
 		NicknameMapper nicknameMapper,
 		ProvinceMapper provinceMapper,
 		Configuration config
 	) {
 		this.characters = characters;
 
 		Id = $"imperatorRegnal{imperatorCountry.Tag}{preImperatorRuler.Name}{rulerTermStart.ToString()[1..]}BC".Replace('.', '_');
 		FromImperator = true;
 		var name = preImperatorRuler.Name ?? Id;
 		SetName(name, null);
 		if (!string.IsNullOrEmpty(name)) {
 			var impNameLoc = irLocDB.GetLocBlockForKey(name);
 			CK3LocBlock ck3NameLoc = ck3LocDB.GetOrCreateLocBlock(name);
 			if (impNameLoc is not null) {
 				ck3NameLoc.CopyFrom(impNameLoc);
 			} else {  // fallback: use unlocalized name as displayed name
 				ck3NameLoc[ConverterGlobals.PrimaryLanguage] = name;
 			}
 		}
 
 		BirthDate = preImperatorRuler.BirthDate!;
 		DeathDate = preImperatorRuler.DeathDate!;
 
 		// determine culture and religion
 		ulong ck3Province = 0;
 		ulong irProvince = 0;
 		var srcReligion = preImperatorRuler.Religion ?? imperatorCountry.Religion;
 		var srcCulture = preImperatorRuler.Culture ?? imperatorCountry.PrimaryCulture;
 		if (imperatorCountry.CapitalProvinceId is not null) {
 			irProvince = imperatorCountry.CapitalProvinceId.Value;
 			var ck3Provinces = provinceMapper.GetCK3ProvinceNumbers(irProvince);
 			if (ck3Provinces.Count > 0) {
 				ck3Province = ck3Provinces[0];
 			}
 		}
 
 		if (srcCulture is not null) {
 			var cultureMatch = cultureMapper.Match(srcCulture, ck3Province, irProvince, imperatorCountry.HistoricalTag);
 			if (cultureMatch is not null) {
 				SetCultureId(cultureMatch, null);
 			}
 		}
 
 		if (srcReligion is not null) {
 			var faithMatch = religionMapper.Match(
 				srcReligion, 
 				GetCultureId(config.CK3BookmarkDate), 
 				ck3Province, 
 				irProvince, 
 				imperatorCountry.HistoricalTag, 
 				config
 			);
 			if (faithMatch is not null) {
 				SetFaithId(faithMatch, null);
 			}
 		}
 
 		var nickname = nicknameMapper.GetCK3NicknameForImperatorNickname(preImperatorRuler.Nickname);
 		if (nickname is not null) {
 			SetNickname(nickname, DeathDate);
 		}
 	}
 
 	internal Character(
 		Imperator.Characters.Character impCharacter,
 		CharacterCollection characters,
 		ReligionMapper religionMapper,
 		CultureMapper cultureMapper,
 		TraitMapper traitMapper,
 		NicknameMapper nicknameMapper,
 		LocDB irLocDB,
 		CK3LocDB ck3LocDB,
 		MapData irMapData,
 		ProvinceMapper provinceMapper,   // used to determine ck3 province for religion mapper
 		DeathReasonMapper deathReasonMapper,
 		DNAFactory dnaFactory,
 		Date dateOnConversion,
 		Configuration config,
 		ISet<string> unlocalizedImperatorNames
 	) {
 		this.characters = characters;
 
 		ImperatorCharacter = impCharacter;
 		ImperatorCharacter.CK3Character = this;
 		Id = "imperator" + ImperatorCharacter.Id;
 		FromImperator = true;
 
 		if (!string.IsNullOrEmpty(ImperatorCharacter.CustomName)) {
 			var loc = ImperatorCharacter.CustomName;
 			var locKey = CommonFunctions.NormalizeUTF8Path(loc.FoldToASCII().Replace(' ', '_'));
 			var name = $"IRTOCK3_CUSTOM_NAME_{locKey}";
 			SetName(name, null);
 
 			var ck3NameLocBlock = ck3LocDB.GetOrCreateLocBlock(name);
 			foreach (var language in ConverterGlobals.SupportedLanguages) {
 				ck3NameLocBlock[language] = loc;
 			}
 		} else {
 			var nameLoc = ImperatorCharacter.Name;
 			var name = nameLoc.Replace(' ', '_');
 			SetName(name, null);
 			if (!string.IsNullOrEmpty(name)) {
 				var ck3NameLocBlock = ck3LocDB.GetOrCreateLocBlock(name);
 				var matchedLocBlock = irLocDB.GetLocBlockForKey(name);
 				if (matchedLocBlock is not null) {
 					ck3NameLocBlock.CopyFrom(matchedLocBlock);
 				} else {  // fallback: use unlocalized name as displayed name
 					unlocalizedImperatorNames.Add(name);
 					ck3NameLocBlock[ConverterGlobals.PrimaryLanguage] = nameLoc;
 				}
 			}
 		}
 
 		Female = ImperatorCharacter.Female;
 
 		// Determine valid (not dropped in province mappings) "source I:R province" and "source CK3 province"
 		// to be used by religion mapper. Don't give up without a fight.
 		ulong? irProvinceId = ImperatorCharacter.GetSourceLandProvince(irMapData);
 
 		var irProvIdForProvMapper = irProvinceId;
 		if (IsImperatorProvIdInvalidForCharacterSource(irProvIdForProvMapper, provinceMapper) && ImperatorCharacter.Father is not null) {
 			irProvIdForProvMapper = ImperatorCharacter.Father.ProvinceId;
 		}
 		if (IsImperatorProvIdInvalidForCharacterSource(irProvIdForProvMapper, provinceMapper) && ImperatorCharacter.Mother is not null) {
 			irProvIdForProvMapper = ImperatorCharacter.Mother.ProvinceId;
 		}
 		if (IsImperatorProvIdInvalidForCharacterSource(irProvIdForProvMapper, provinceMapper) && ImperatorCharacter.Spouses.Count > 0) {
-			var firstSpouse = ImperatorCharacter.Spouses.First().Value;
+			var firstSpouse = ImperatorCharacter.Spouses.AsValueEnumerable().First().Value;
 			irProvIdForProvMapper = firstSpouse.ProvinceId;
 		}
 
 		var ck3ProvinceNumbers = irProvIdForProvMapper.HasValue ? provinceMapper.GetCK3ProvinceNumbers(irProvIdForProvMapper.Value) : [];
 		ulong? ck3ProvinceId = ck3ProvinceNumbers.Count > 0 ? ck3ProvinceNumbers[0] : null;
 
 		var cultureMatch = cultureMapper.Match(
 			ImperatorCharacter.Culture,
 			ck3ProvinceId,
 			irProvinceId,
 			ImperatorCharacter.Country?.HistoricalTag
 		);
 		if (cultureMatch is null) {
 			Logger.Warn($"Could not determine CK3 culture for Imperator character {ImperatorCharacter.Id}" +
 			            $" with culture {ImperatorCharacter.Culture}!");
 		} else {
 			SetCultureId(cultureMatch, null);
 		}
 
 		var faithMatch = religionMapper.Match(
 			ImperatorCharacter.Religion,
 			GetCultureId(dateOnConversion),
 			ck3ProvinceId, 
 			irProvinceId,
 			ImperatorCharacter.HomeCountry?.HistoricalTag,
 			config
 		);
 		if (faithMatch is not null) {
 			SetFaithId(faithMatch, null);
 		}
 
 		// Determine character attributes.
 		History.AddFieldValue(null, "diplomacy", "diplomacy", ImperatorCharacter.Attributes.Charisma);
 		History.AddFieldValue(null, "martial", "martial", ImperatorCharacter.Attributes.Martial);
 		History.AddFieldValue(null, "stewardship", "stewardship", ImperatorCharacter.Attributes.Finesse);
 		var intrigue = (ImperatorCharacter.Attributes.Finesse + ImperatorCharacter.Attributes.Charisma) / 2;
 		History.AddFieldValue(null, "intrigue", "intrigue", intrigue);
 		History.AddFieldValue(null, "learning", "learning", ImperatorCharacter.Attributes.Zeal);
 
 		if (impCharacter.Fertility.HasValue) {
 			History.AddFieldValue(null, "fertility", "fertility", impCharacter.Fertility.Value);
 		}
 
 		if (impCharacter.Health is not null) {
 			// In I:R, health is a value between 0 and 100, with 100 being the best.
 			// In CK3, 0 means near death, ≥ 7 means excellent health.
 			// https://imperator.paradoxwikis.com/Characters#Secondary
 			// https://ck3.paradoxwikis.com/Attributes#Health
 			var ck3Health = impCharacter.Health.Value / 10;
 			History.AddFieldValue(null, "health", "health", ck3Health);
 		}
 
 		foreach (var traitId in traitMapper.GetCK3TraitsForImperatorTraits(ImperatorCharacter.Traits)) {
 			AddBaseTrait(traitId);
 		}
 
 		BirthDate = ImperatorCharacter.BirthDate;
 		DeathDate = ImperatorCharacter.DeathDate;
 		var impDeathReason = ImperatorCharacter.DeathReason;
 		if (impDeathReason is not null) {
 			DeathReason = deathReasonMapper.GetCK3ReasonForImperatorReason(impDeathReason);
 		}
 
 		var nicknameMatch = nicknameMapper.GetCK3NicknameForImperatorNickname(ImperatorCharacter.Nickname);
 		if (nicknameMatch is not null) {
 			var nicknameDate = ImperatorCharacter.DeathDate ?? dateOnConversion;
 			SetNickname(nicknameMatch, nicknameDate);
 		}
 
 		if (ImperatorCharacter.Wealth != 0) {
 			Gold = ImperatorCharacter.Wealth * config.ImperatorCurrencyRate;
 		}
 
 		// If character is imprisoned, set jailor.
 		SetJailor();
 		SetEmployerFromImperator();
 
 		void SetJailor() {
 			if (ImperatorCharacter.PrisonerHome is null) {
 				return;
 			}
 
 			var prisonCountry = ImperatorCharacter.Country;
 			if (prisonCountry is null) {
 				Logger.Warn($"Imperator character {ImperatorCharacter.Id} is imprisoned but has no country!");
 			} else if (prisonCountry.CK3Title is null) {
 				Logger.Debug($"Imperator character {ImperatorCharacter.Id}'s prison country does not exist in CK3!");
 			} else {
 				jailorId = prisonCountry.CK3Title.GetHolderId(dateOnConversion);
 			}
 		}
 
 		void SetEmployerFromImperator() {
 			var prisonerHome = ImperatorCharacter.PrisonerHome;
 			var homeCountry = ImperatorCharacter.HomeCountry;
 			if (prisonerHome?.CK3Title is not null) { // is imprisoned
 				SetEmployerId(prisonerHome.CK3Title.GetHolderId(dateOnConversion), null);
 			} else if (homeCountry?.CK3Title is not null) {
 				SetEmployerId(homeCountry.CK3Title.GetHolderId(dateOnConversion), null);
 			}
 		}
 	}
 
 	private static bool IsImperatorProvIdInvalidForCharacterSource(ulong? impProvForProvinceMapper, ProvinceMapper provinceMapper) {
 		return !impProvForProvinceMapper.HasValue || provinceMapper.GetCK3ProvinceNumbers(impProvForProvinceMapper.Value).Count == 0;
 	}
@@ -579,11 +579,11 @@
 
 	public void RemoveAllChildren() {
 		if (Female) {
-			foreach (var child in childrenCache.Where(c => c.MotherId == Id)) {
+			foreach (var child in childrenCache.AsValueEnumerable().Where(c => c.MotherId == Id)) {
 				child.Mother = null;
 			}
 		} else {
-			foreach (var child in childrenCache.Where(c => c.FatherId == Id)) {
+			foreach (var child in childrenCache.AsValueEnumerable().Where(c => c.FatherId == Id)) {
 				child.Father = null;
 			}
 		}
@@ -690,7 +690,7 @@
 		}
 	}
 
-	public IReadOnlyCollection<Character> Children => characters
+	public IReadOnlyCollection<Character> Children => characters.AsValueEnumerable()
 		.Where(c => c.FatherId == Id || c.MotherId == Id)
 		.ToImmutableList();
 
@@ -802,7 +802,7 @@
 				sb.AppendLine($"\t\t\tmen_at_arms={{type={type} men={men}}}");
 			}
 
-			var ck3Location = provinceMapper.GetCK3ProvinceNumbers(unit.Location)
+			var ck3Location = provinceMapper.GetCK3ProvinceNumbers(unit.Location).AsValueEnumerable()
 				.Cast<ulong?>()
 				.FirstOrDefault(defaultValue: null);
 			if (ck3Location is not null) {

ImperatorToCK3/CK3/Characters/CharacterCollection.cs

@@ -19,6 +19,7 @@
 using Open.Collections;
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text.RegularExpressions;
@@ -266,8 +267,8 @@
 			return conversionDate;
 		}
 		Date? GetBirthDateOfFirstCommonChild(Imperator.Characters.Character father, Imperator.Characters.Character mother) {
-			var childrenOfFather = father.Children.Values.ToHashSet();
-			var childrenOfMother = mother.Children.Values.ToHashSet();
+			var childrenOfFather = father.Children.Values.ToFrozenSet();
+			var childrenOfMother = mother.Children.Values.ToFrozenSet();
 			var commonChildren = childrenOfFather.Intersect(childrenOfMother).OrderBy(child => child.BirthDate).ToArray();
 
 			Date? firstChildBirthDate = commonChildren.Length > 0 ? commonChildren.FirstOrDefault()?.BirthDate : null;
@@ -382,54 +383,54 @@
 		Logger.IncrementProgress();
 	}
 
 	private void SetCharacterCastes(CultureCollection cultures, Date ck3BookmarkDate) {
 		var casteSystemCultureIds = cultures
 			.Where(c => c.TraditionIds.Contains("tradition_caste_system"))
 			.Select(c => c.Id)
-			.ToHashSet();
+			.ToFrozenSet();
 		var learningEducationTraits = new[]{"education_learning_1", "education_learning_2", "education_learning_3", "education_learning_4"};
 
 		foreach (var character in this.OrderBy(c => c.BirthDate)) {
 			if (character.ImperatorCharacter is null) {
 				continue;
 			}
 
 			var cultureId = character.GetCultureId(ck3BookmarkDate);
 			if (cultureId is null || !casteSystemCultureIds.Contains(cultureId)) {
 				continue;
 			}
 
 			// The caste is hereditary.
 			var father = character.Father;
 			if (father is not null) {
 				var foundTrait = GetCasteTraitFromParent(father);
 				if (foundTrait is not null) {
 					character.AddBaseTrait(foundTrait);
 					continue;
 				}
 			}
 			var mother = character.Mother;
 			if (mother is not null) {
 				var foundTrait = GetCasteTraitFromParent(mother);
 				if (foundTrait is not null) {
 					character.AddBaseTrait(foundTrait);
 					continue;
 				}
 			}
 
 			// Try to set caste based on character's traits.
-			var traitIds = character.BaseTraits.ToHashSet();
+			var traitIds = character.BaseTraits.ToFrozenSet();
 			character.AddBaseTrait(traitIds.Intersect(learningEducationTraits).Any() ? "brahmin" : "kshatriya");
 		}
 		return;
 
 		static string? GetCasteTraitFromParent(Character parentCharacter) {
 			var casteTraits = new[]{"brahmin", "kshatriya", "vaishya", "shudra"};
-			var parentTraitIds = parentCharacter.BaseTraits.ToHashSet();
+			var parentTraitIds = parentCharacter.BaseTraits.ToFrozenSet();
 			return casteTraits.Intersect(parentTraitIds).FirstOrDefault();
 		}
 	}
 
 	public void LoadCharacterIDsToPreserve(Date ck3BookmarkDate) {
 		Logger.Debug("Loading IDs of CK3 characters to preserve...");
 
@@ -468,93 +469,93 @@
 		parser.ParseFile(configurablePath);
 	}
 
 	public void PurgeUnneededCharacters(Title.LandedTitles titles, DynastyCollection dynasties, HouseCollection houses, Date ck3BookmarkDate) {
 		Logger.Info("Purging unneeded characters...");
 
 		// Characters from CK3 that hold titles at the bookmark date should be kept.
 		var currentTitleHolderIds = titles.GetHolderIdsForAllTitlesExceptNobleFamilyTitles(ck3BookmarkDate);
 		var landedCharacters = this
 			.Where(character => currentTitleHolderIds.Contains(character.Id))
 			.ToArray();
 		var charactersToCheck = this.Except(landedCharacters);
 
 		// Characters from I:R that held or hold titles should be kept.
 		var allTitleHolderIds = titles.GetAllHolderIds();
 		var imperatorTitleHolders = this
 			.Where(character => character.FromImperator && allTitleHolderIds.Contains(character.Id))
 			.ToArray();
 		charactersToCheck = charactersToCheck.Except(imperatorTitleHolders);
 
 		// Don't purge animation_test characters.
 		charactersToCheck = charactersToCheck
 			.Where(c => !c.Id.StartsWith("animation_test_"));
 
 		// Keep alive Imperator characters.
 		charactersToCheck = charactersToCheck
 			.Where(c => c is not {FromImperator: true, ImperatorCharacter.IsDead: false});
 
 		// Make some exceptions for characters referenced in game's script files.
 		charactersToCheck = charactersToCheck
 			.Where(character => !character.IsNonRemovable)
 			.ToArray();
 
 		// I:R members of landed dynasties will be preserved, unless dead and childless.
 		var dynastyIdsOfLandedCharacters = landedCharacters
 			.Select(character => character.GetDynastyId(ck3BookmarkDate))
 			.Distinct()
 			.Where(id => id is not null)
-			.ToHashSet();
+			.ToFrozenSet();
 
 		var i = 0;
 		var charactersToRemove = new List<Character>();
 		var parentIdsCache = new HashSet<string>();
 		do {
 			Logger.Debug($"Beginning iteration {i} of characters purge...");
 			charactersToRemove.Clear();
 			parentIdsCache.Clear();
 			++i;
 
 			// Build cache of all parent IDs.
 			foreach (var character in this) {
 				var motherId = character.MotherId;
 				if (motherId is not null) {
 					parentIdsCache.Add(motherId);
 				}
 
 				var fatherId = character.FatherId;
 				if (fatherId is not null) {
 					parentIdsCache.Add(fatherId);
 				}
 			}
 
 			// See who can be removed.
 			foreach (var character in charactersToCheck) {
 				// Is the character from Imperator and do they belong to a dynasty that holds or held titles?
 				if (character.FromImperator && dynastyIdsOfLandedCharacters.Contains(character.GetDynastyId(ck3BookmarkDate))) {
 					// Is the character dead and childless? Purge.
 					if (!parentIdsCache.Contains(character.Id)) {
 						charactersToRemove.Add(character);
 					}
 
 					continue;
 				}
 
 				charactersToRemove.Add(character);
 			}
 
 			BulkRemove(charactersToRemove.ConvertAll(c => c.Id));
 
 			Logger.Debug($"\tPurged {charactersToRemove.Count} unneeded characters in iteration {i}.");
 			charactersToCheck = charactersToCheck.Except(charactersToRemove).ToArray();
 		} while(charactersToRemove.Count > 0);
 
 		// At this point we probably have many dynasties with no characters left.
 		// Let's purge them.
 		houses.PurgeUnneededHouses(this, ck3BookmarkDate);
 		dynasties.PurgeUnneededDynasties(this, houses, ck3BookmarkDate);
 		dynasties.FlattenDynastiesWithNoFounders(this, houses, ck3BookmarkDate);
 	}
 
 	public void RemoveEmployerIdFromLandedCharacters(Title.LandedTitles titles, Date conversionDate) {
 		Logger.Info("Removing employer id from landed characters...");
 		var landedCharacterIds = titles.GetHolderIdsForAllTitlesExceptNobleFamilyTitles(conversionDate);
@@ -595,7 +596,7 @@
 			var vassalCharacterIds = ck3Country.GetDeFactoVassals(bookmarkDate).Values
 				.Where(vassalTitle => !vassalTitle.Landless)
 				.Select(vassalTitle => vassalTitle.GetHolderId(bookmarkDate))
-				.ToHashSet();
+				.ToFrozenSet();
 
 			var vassalCharacters = new HashSet<Character>();
 			foreach (var vassalCharacterId in vassalCharacterIds) {
@@ -661,154 +662,154 @@
 		Logger.IncrementProgress();
 	}
 
 	public void GenerateSuccessorsForOldCharacters(Title.LandedTitles titles, CultureCollection cultures, Date irSaveDate, Date ck3BookmarkDate, ulong randomSeed) {
 		Logger.Info("Generating successors for old characters...");
 
 		var oldCharacters = this
 			.Where(c => c.BirthDate < ck3BookmarkDate && c.DeathDate is null && ck3BookmarkDate.DiffInYears(c.BirthDate) > 60).ToArray();
 
 		var titleHolderIds = titles.GetHolderIdsForAllTitlesExceptNobleFamilyTitles(ck3BookmarkDate);
 
 		var oldTitleHolders = oldCharacters
 			.Where(c => titleHolderIds.Contains(c.Id))
 			.ToArray();
 
 		// For characters that don't hold any titles, just set up a death date.
 		var randomForCharactersWithoutTitles = new Random((int)randomSeed);
 		foreach (var oldCharacter in oldCharacters.Except(oldTitleHolders)) {
 			// Roll a dice to determine how much longer the character will live.
 			var yearsToLive = randomForCharactersWithoutTitles.Next(0, 30);
 
 			// If the character is female and pregnant, make sure she doesn't die before the pregnancy ends.
 			if (oldCharacter is {Female: true, ImperatorCharacter: not null}) {
 				var lastPregnancy = oldCharacter.Pregnancies.OrderBy(p => p.BirthDate).LastOrDefault();
 				if (lastPregnancy is not null) {
 					oldCharacter.DeathDate = lastPregnancy.BirthDate.ChangeByYears(yearsToLive);
 					continue;
 				}
 			}
 
 			oldCharacter.DeathDate = irSaveDate.ChangeByYears(yearsToLive);
 		}
 
 		ConcurrentDictionary<string, Title[]> titlesByHolderId = new(titles
 			.Select(t => new {Title = t, HolderId = t.GetHolderId(ck3BookmarkDate)})
 			.Where(t => t.HolderId != "0")
 			.GroupBy(t => t.HolderId)
 			.ToDictionary(g => g.Key, g => g.Select(t => t.Title).ToArray()));
 
 		ConcurrentDictionary<string, string[]> cultureIdToMaleNames = new(cultures
 			.ToDictionary(c => c.Id, c => c.MaleNames.ToArray()));
 
 		// For title holders, generate successors and add them to title history.
 		Parallel.ForEach(oldTitleHolders, oldCharacter => {
 			// Get all titles held by the character.
 			var heldTitles = titlesByHolderId[oldCharacter.Id];
 			string? dynastyId = oldCharacter.GetDynastyId(ck3BookmarkDate);
 			string? dynastyHouseId = oldCharacter.GetDynastyHouseId(ck3BookmarkDate);
 			string? faithId = oldCharacter.GetFaithId(ck3BookmarkDate);
 			string? cultureId = oldCharacter.GetCultureId(ck3BookmarkDate);
 			string[] maleNames;
 			if (cultureId is not null) {
 				maleNames = cultureIdToMaleNames[cultureId];
 			} else {
 				Logger.Warn($"Failed to find male names for successors of {oldCharacter.Id}.");
 				maleNames = ["Alexander"];
 			}
 
 			var randomSeedForCharacter = randomSeed ^ (oldCharacter.ImperatorCharacter?.Id ?? 0);
 			var random = new Random((int)randomSeedForCharacter);
 
 			int successorCount = 0;
 			Character currentCharacter = oldCharacter;
 			Date currentCharacterBirthDate = currentCharacter.BirthDate;
 			while (ck3BookmarkDate.DiffInYears(currentCharacterBirthDate) >= 90) {
 				// If the character has living male children, the oldest one will be the successor.
 				var successorAndBirthDate = currentCharacter.Children
 					.Where(c => c is {Female: false, DeathDate: null})
 					.Select(c => new { Character = c, c.BirthDate })
 					.OrderBy(x => x.BirthDate)
 					.FirstOrDefault();
 
 				Character successor;
 				Date currentCharacterDeathDate;
 				Date successorBirthDate;
 				if (successorAndBirthDate is not null) {
 					successor = successorAndBirthDate.Character;
 					successorBirthDate = successorAndBirthDate.BirthDate;
 
 					// Roll a dice to determine how much longer the character will live.
 					// But make sure the successor is at least 16 years old when the old character dies.
 					var successorAgeAtBookmarkDate = ck3BookmarkDate.DiffInYears(successorBirthDate);
 					var yearsUntilSuccessorBecomesAnAdult = Math.Max(16 - successorAgeAtBookmarkDate, 0);
 
 					var yearsToLive = random.Next((int)Math.Ceiling(yearsUntilSuccessorBecomesAnAdult), 25);
 					int currentCharacterAge = random.Next(30 + yearsToLive, 80);
 					currentCharacterDeathDate = currentCharacterBirthDate.ChangeByYears(currentCharacterAge);
 					// Needs to be after the save date.
 					if (currentCharacterDeathDate <= irSaveDate) {
 						currentCharacterDeathDate = irSaveDate.ChangeByDays(1);
 					}
 				} else {
 					// We don't want all the generated successors on the map to have the same birth date.
 					var yearsUntilHeir = random.Next(1, 5);
 
 					// Make the old character live until the heir is at least 16 years old.
 					var successorAge = random.Next(yearsUntilHeir + 16, 30);
 					int currentCharacterAge = random.Next(30 + successorAge, 80);
 					currentCharacterDeathDate = currentCharacterBirthDate.ChangeByYears(currentCharacterAge);
 					if (currentCharacterDeathDate <= irSaveDate) {
 						currentCharacterDeathDate = irSaveDate.ChangeByDays(1);
 					}
 
 					// Generate a new successor.
 					string id = $"irtock3_{oldCharacter.Id}_successor_{successorCount}";
 					string firstName = maleNames[random.Next(0, maleNames.Length)];
 
 					successorBirthDate = currentCharacterDeathDate.ChangeByYears(-successorAge);
 					successor = new Character(id, firstName, successorBirthDate, this) {FromImperator = true};
 					Add(successor);
 					if (currentCharacter.Female) {
 						successor.Mother = currentCharacter;
 					} else {
 						successor.Father = currentCharacter;
 					}
 					if (cultureId is not null) {
 						successor.SetCultureId(cultureId, null);
 					}
 					if (faithId is not null) {
 						successor.SetFaithId(faithId, null);
 					}
 					if (dynastyId is not null) {
 						successor.SetDynastyId(dynastyId, null);
 					}
 					if (dynastyHouseId is not null) {
 						successor.SetDynastyHouseId(dynastyHouseId, null);
 					}
 				}
 
 				currentCharacter.DeathDate = currentCharacterDeathDate;
 				// On the old character death date, the successor should inherit all titles.
 				foreach (var heldTitle in heldTitles) {
 					heldTitle.SetHolder(successor, currentCharacterDeathDate);
 				}
 
 				// Move to the successor and repeat the process.
 				currentCharacter = successor;
 				currentCharacterBirthDate = successorBirthDate;
 				++successorCount;
 			}
 
 			// After the loop, currentCharacter should represent the successor at bookmark date.
 			// Set his DNA to avoid weird looking character on the bookmark screen in CK3.
 			currentCharacter.DNA = oldCharacter.DNA;
 
 			// Transfer gold to the living successor.
 			currentCharacter.Gold = oldCharacter.Gold;
 			oldCharacter.Gold = null;
 		});
 	}
 
 	internal void ConvertImperatorCharacterDNA(DNAFactory dnaFactory) {
 		Logger.Info("Converting Imperator character DNA to CK3...");
 		foreach (var character in this) {
@@ -830,7 +831,7 @@
 	public void RemoveUndefinedTraits(TraitMapper traitMapper) {
 		Logger.Info("Removing undefined traits from CK3 character history...");
 
-		var definedTraits = traitMapper.ValidCK3TraitIDs.ToHashSet();
+		var definedTraits = traitMapper.ValidCK3TraitIDs.ToFrozenSet();
 
 		foreach (var character in this) {
 			if (character.FromImperator) {
@@ -849,7 +850,7 @@
 		Logger.Info("Removing invalid dynasties from CK3 character history...");
 
 		var ck3Characters = this.Where(c => !c.FromImperator).ToArray();
-		var validDynastyIds = dynasties.Select(d => d.Id).ToHashSet();
+		var validDynastyIds = dynasties.Select(d => d.Id).ToFrozenSet();
 
 		foreach (var character in ck3Characters) {
 			if (!character.History.Fields.TryGetValue("dynasty", out var dynastyField)) {

ImperatorToCK3/CK3/Characters/CharactersLoader.cs

@@ -1,8 +1,9 @@
 using commonItems;
 using commonItems.Mods;
 using Open.Collections.Synchronized;
+using System.Collections.Frozen;
 using System.Collections.Generic;
-using System.Linq;
+using ZLinq;
 
 namespace ImperatorToCK3.CK3.Characters;
 
@@ -51,8 +52,10 @@ public void LoadCK3Characters(ModFilesystem ck3ModFS, Date bookmarkDate) {
 			"claims",
 		];
 
-		var femaleCharacterIds = loadedCharacters.Where(c => c.Female).Select(c => c.Id).ToHashSet();
-		var maleCharacterIds = loadedCharacters.Select(c => c.Id).Except(femaleCharacterIds).ToHashSet();
+		var femaleCharacterIds = loadedCharacters.AsValueEnumerable()
+			.Where(c => c.Female).Select(c => c.Id).ToFrozenSet();
+		var maleCharacterIds = loadedCharacters.AsValueEnumerable()
+			.Select(c => c.Id).Except(femaleCharacterIds).ToFrozenSet();
 
 		foreach (var character in loadedCharacters) {
 			// Clear some fields we don't need.
@@ -91,7 +94,8 @@ public void LoadCK3Characters(ModFilesystem ck3ModFS, Date bookmarkDate) {
 
 			// Remove effects that set relations. They don't matter a lot in our alternate timeline.
 			character.History.Fields["effects"].RemoveAllEntries(
-				entry => irrelevantEffects.Any(effect => entry.ToString()?.Contains(effect) ?? false));
+				entry => irrelevantEffects.AsValueEnumerable()
+					.Any(effect => entry.ToString()?.Contains(effect) ?? false));
 
 			// Fix characters being set as their own fathers/mothers.
 			if (character.FatherId == character.Id) {
@@ -111,7 +115,7 @@ public void LoadCK3Characters(ModFilesystem ck3ModFS, Date bookmarkDate) {
 		Logger.Info("Loaded CK3 characters.");
 	}
 
-	private static void RemoveInvalidMotherAndFatherEntries(Character character, HashSet<string> femaleCharacterIds, HashSet<string> maleCharacterIds) {
+	private static void RemoveInvalidMotherAndFatherEntries(Character character, FrozenSet<string> femaleCharacterIds, FrozenSet<string> maleCharacterIds) {
 		// Remove wrong sex mother and father references (male mothers, female fathers).
 		var motherField = character.History.Fields["mother"];
 		motherField.RemoveAllEntries(value => {

ImperatorToCK3/CK3/Cultures/Culture.cs

@@ -4,6 +4,7 @@
 using commonItems.Serialization;
 using ImperatorToCK3.Mappers.Technology;
 using Open.Collections;
+using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -103,7 +104,7 @@ public async Task OutputHistory(string outputModPath, Date date) {
 		await historyWriter.WriteAsync(historyStrBuilder.ToString());
 	}
 
-	public void ImportInnovationsFromImperator(ISet<string> irInventions, InnovationMapper innovationMapper) {
+	public void ImportInnovationsFromImperator(FrozenSet<string> irInventions, InnovationMapper innovationMapper) {
 		innovationsFromImperator.AddRange(innovationMapper.GetInnovations(irInventions));
 
 		var progresses = innovationMapper.GetInnovationProgresses(irInventions);

ImperatorToCK3/CK3/Cultures/CultureCollection.cs

@@ -11,6 +11,7 @@
 using ImperatorToCK3.Mappers.Province;
 using ImperatorToCK3.Mappers.Technology;
 using System;
+using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -226,7 +227,7 @@
 		return cultureMapper.Match(irCulture, ck3ProvinceId, irProvinceId, country.HistoricalTag);
 	}
 
 	public void ImportTechnology(CountryCollection countries, CultureMapper cultureMapper, ProvinceMapper provinceMapper, InventionsDB inventionsDB, LocDB irLocDB, OrderedDictionary<string, bool> ck3ModFlags) { // TODO: add tests for this
 		Logger.Info("Converting Imperator inventions to CK3 innovations...");
 
 		var innovationMapper = new InnovationMapper();
@@ -249,7 +250,7 @@
 
 			var irInventions = grouping
 				.SelectMany(c => c.Country.GetActiveInventionIds(inventionsDB))
-				.ToHashSet();
+				.ToFrozenSet();
 			culture.ImportInnovationsFromImperator(irInventions, innovationMapper);
 		}
 	}