diff --git a/bun.lock b/bun.lock
index ca198071..885763f4 100644
--- a/bun.lock
+++ b/bun.lock
@@ -31,6 +31,7 @@
         "dotenv": "^16.4.5",
         "dotenv-cli": "^7.4.2",
         "firebase-admin": "^12.2.0",
+        "lru-cache": "^11.0.2",
         "hono": "^4.7.1",
         "sharp": "^0.33.5",
         "socket.io": "^4.7.5",
@@ -902,7 +903,7 @@
 
     "loose-envify": ["loose-envify@1.4.0", "", { "dependencies": { "js-tokens": "^3.0.0 || ^4.0.0" }, "bin": { "loose-envify": "cli.js" } }, "sha512-lyuxPGr/Wfhrlem2CL/UcnUc1zcqKAImBDzukY7Y5F/yQiNdko6+fRLevlw1HgMySw7f611UIY408EtxRSoK3Q=="],
 
-    "lru-cache": ["lru-cache@6.0.0", "", { "dependencies": { "yallist": "^4.0.0" } }, "sha512-Jo6dJ04CmSjuznwJSS3pUeWmd/H0ffTlkXXgwZi+eq1UCmqQwCh+eLsYOYCwY991i2Fah4h1BEMCx4qThGbsiA=="],
+    "lru-cache": ["lru-cache@11.0.2", "", {}, "sha512-123qHRfJBmo2jXDbo/a5YOQrJoHF/GNQTLzQ5+IdK5pWpceK17yRc6ozlWd25FxvGKQbIUs91fDFkXmDHTKcyA=="],
 
     "lru-memoizer": ["lru-memoizer@2.3.0", "", { "dependencies": { "lodash.clonedeep": "^4.5.0", "lru-cache": "6.0.0" } }, "sha512-GXn7gyHAMhO13WSKrIiNfztwxodVsP8IoZ3XfrJV4yH2x0/OeTO/FIaAHTY5YekdGgW94njfuKmyyt1E0mR6Ug=="],
 
@@ -1274,6 +1275,8 @@
 
     "log-update/slice-ansi": ["slice-ansi@7.1.0", "", { "dependencies": { "ansi-styles": "^6.2.1", "is-fullwidth-code-point": "^5.0.0" } }, "sha512-bSiSngZ/jWeX93BqeIAbImyTbEihizcwNjFoRUIY/T1wWQsfsm2Vw1agPKylXvQTU7iASGdHhyqRlqQzfz+Htg=="],
 
+    "lru-memoizer/lru-cache": ["lru-cache@6.0.0", "", { "dependencies": { "yallist": "^4.0.0" } }, "sha512-Jo6dJ04CmSjuznwJSS3pUeWmd/H0ffTlkXXgwZi+eq1UCmqQwCh+eLsYOYCwY991i2Fah4h1BEMCx4qThGbsiA=="],
+
     "nearley/commander": ["commander@2.20.3", "", {}, "sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ=="],
 
     "next/postcss": ["postcss@8.4.31", "", { "dependencies": { "nanoid": "^3.3.6", "picocolors": "^1.0.0", "source-map-js": "^1.0.2" } }, "sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ=="],
diff --git a/server/package.json b/server/package.json
index 3e4c2865..2a056c65 100644
--- a/server/package.json
+++ b/server/package.json
@@ -24,6 +24,7 @@
     "dotenv": "^16.4.5",
     "dotenv-cli": "^7.4.2",
     "firebase-admin": "^12.2.0",
+    "lru-cache": "^11.0.2",
     "hono": "^4.7.1",
     "sharp": "^0.33.5",
     "socket.io": "^4.7.5",
diff --git a/server/src/firebase/auth/db.ts b/server/src/firebase/auth/db.ts
index eb207415..9f4865a5 100644
--- a/server/src/firebase/auth/db.ts
+++ b/server/src/firebase/auth/db.ts
@@ -1,24 +1,23 @@
-import type { IDToken, UserID } from "common/types";
-import { getGUID, getGUIDFromToken } from "./lib";
-
+import type { GUID, IDToken, UserID } from "common/types";
 import type { Context } from "hono";
+import { LRUCache } from "lru-cache";
 import { prisma } from "../../database/client";
 import { error } from "../../lib/error";
-/**
- * REQUIRE: cookieParser middleware before this
- * THROWS: if idToken is not present in request cookie, or when the token is not valid.
- * Expected use case:
- * ```js
- * let userId: number;
- * try {
- *   userId = await getUserId(req);
- * } catch {
- *   return res.status(401).send("auth error");
- * }
- * ```
- **/
+import { getGUID, getGUIDFromToken } from "./lib";
+
+const guid_userid_cache = new LRUCache<GUID, UserID>({
+  max: 100,
+});
+
 export async function getUserId(c: Context): Promise<UserID> {
   const guid = await getGUID(c);
+
+  const cache = guid_userid_cache.get(guid);
+  if (cache) {
+    console.log(`[CACHE HIT] ${guid} -> ${cache}`);
+    return cache;
+  }
+
   const user = await prisma.user.findUnique({
     where: {
       guid: guid,
@@ -28,17 +27,28 @@ export async function getUserId(c: Context): Promise<UserID> {
     },
   });
   if (!user) error("auth error: unauthorized", 401);
+  guid_userid_cache.set(guid, user.id);
   return user.id;
 }
 
 export async function getUserIdFromToken(token: IDToken): Promise<UserID> {
   const guid = await getGUIDFromToken(token);
+
+  const cache = guid_userid_cache.get(guid);
+  if (cache) {
+    return cache;
+  }
+
   const user = await prisma.user.findUnique({
     where: {
       guid: guid,
     },
+    select: {
+      id: true,
+    },
   });
   if (!user) error("User not found!", 401);
+  guid_userid_cache.set(guid, user.id);
   return user.id;
 }