I have quite a different experience, can't tell if it is placebo or not, but my vr experience is slightly smoother in Arch Linux compared to my Windows 10.
i play VR via Proton using ALVR (steamvr) or Wivrn
But i havent tried playing Alyx on linux yet
What's wrong with webp? It support animation, lossless compression, lossy compression and transparency. Animation has a smaller size than gif.