Migrate to Bun

[WarningImHack3r]

As Bun 1.0 is officially out and we are always the first to opt-in to the latest technologies, let's try it and see if we can get better performance!

We don't have much to change as Bun is a drop-in replacement and we don't use many components that Bun replaces, so it's pretty straightforward.

Changes

• Replace pnpm with Bun in the lock file and CI
• Change from @sveltejs/adapter-static to svelte-adapter-bun (that should work the same)
• Add .gitattributes for optimal lock file support

Speed gains

What will be impacted

• Dependencies installation (both locally and in CI, you're welcome, GitHub)
  • As the install process in CI is much easier than for pnpm, the Unlighthouse step now uses Bun and will thus be significantly faster
• Startup times of package.json scripts

What won't be impacted

• Website speed: As the output is static anyway, there won't be any change on that side. If we were to host it on a "Node" server, however, we would notice a significant improvement
• All the rest

---

What's needed before merge

• Find a way to ensure the other non-PR CI jobs won't break
• Wait for the soon-to-be Windows port for @MinixBF? (or if it's fine enough to use WSL)
• Check that it's compatible with static GitHub Pages we don't have any bun-specific feature in src, should be fine
• Make a last tour on what could be migrated/improved

Note

To optimize support for bun.lockb by git, add this to your global configuration (source):

git config --global diff.lockb.textconv bun
git config --global diff.lockb.binary true

[WarningImHack3r]

First speed test comparison

Dependencies installation (Husky included - from scratch)

pnpm i ➜ bun i (macOS): 13s ➜ 0.5-4s
pnpm i ➜ bun i (CI): 2.5s ➜ 1-3s

Build

macOS: 21s ➜ 22s
CI: 1m10s ➜ 1m5s

Note
The build time is almost unchanged apart from a few ms to start the vite command.
90% of our build time is due to the svelte-icons dependency anyway.

CI Node+pnpm / Bun installation (Husky included)

Before: 8s
After: 1-3s

Unlighthouse check

Before: 1m15s
After: 50s

Overall CI improvements (PR only)

Before: 2m10s
After: 1m40s

[WarningImHack3r]

Follow-up for SSG (GitHub Pages) support: gornostay25/svelte-adapter-bun#26

[WarningImHack3r]

This migration is finally ready to be performed.
I can't wait to be blazingly fast 🏎️

One last doubt: I often see (and I experienced it) people complaining about some little different behaviors between Node and Bun, that the Bun team is well aware of and actively working on. I'm a bit hesitant because for now, everything's good, however, nothing guarantees that we won't stumble across a similar issue someday... Do we need to wait a little more? Do we care? Couldn't we simply revert this PR if something goes wrong? I don't know...

[MinixBF]

I finally tested it and reviewed it, it works perfectly. Well done! 👋
I'm ready to migrate when you think it will be good (I have less hindsight on this).