Tectonic Speed Decrease Since Version 0.9.0

[ktzanev]

For years, I have been using Tectonic 0.8.2 because it is the last "fast" version. Since version 0.9.0, the compilation speed has significantly dropped. Interestingly, the speed of version 0.7.1 was even better than 0.8.2, but unfortunately, I can no longer use this version due to the following error:

error: unexpected HTTP response code 403 Forbidden for URL https://archive.org/services/purl/net/pkgwpub/tectonic-default

This brings up another issue: one of the main goals of Tectonic is to be reproducible. However, we can't use old versions anymore because the package repository is no longer available.

I have tested different versions with Hyperfine under Windows using the following bash script:

#!/bin/sh

# This script is used to test the speed of different tectonic versions
# it use hyperfine to run the test

# versions to test
versions=(
    "0.8.0"
    "0.8.2"
    "0.9.0"
    "0.11.0"
    "0.12.0"
    "0.15.0"
)

path="/c/bin"

# run the test
for version in "${versions[@]}"
do
    echo "Testing..."
    exe="$path/tectonic.$version.exe"
    "$exe" --version
    hyperfine --warmup 3 --ignore-failure -N --export-json "tectonic-$version.json" "$exe test.tex"
    echo "Done"
done

The results are as follows:

Version	Time (s)
0.8.0	1.671
0.8.2	1.691
0.9.0	2.800
0.11.0	2.286
0.12.0	2.348
0.15.0	2.304

I tested this with a "real" LaTeX document that produces 4 pages with one logo.

My questions are:

1. Is the speed decrease only a Windows problem?
2. Does anyone have any idea why this happens and if there is any chance to go back to the speed of the first versions of Tectonic?

---

[CraftSpider]

0.9 included a version bump of the backing XeTeX engine, as well as xdvipdfmx. I can try to investigate when I have the chance whether the slowdown appears to be part of a change to tectonic, or to the backing engine. If it's part of the Rust code of Tectonic I'll try to fix it. If not, eventually the port to Rust initiative should reach the XeTeX engine, at which point I can look into optimizing it.

[ktzanev]

Thanks for looking into this. 🙏
I'd appreciate any speed improvements in future versions. 🚀