Comment 11 for bug 1847069

I'm also experiencing very slow Chromium with the new Snap (both during startup and stuttering during runtime). I've done some cursory profiling and it looks like the culprit is SquashFS with lzma. LZMA by itself is very slow to decompress (zstd would be much more appropriate for snaps, being much faster and only a tiny bit bigger) and SquashFS is very slow because of the way IO is done and caching. Google even carries custom patches for Android (https://android-review.googlesource.com/q/topic:squashfs) since it's so slow, but they weren't upstreamed because they removed an old caching mechanism that the maintainers wanted to keep (https://lore.kernel.org/patchwork/patch/833639/).

If Ubuntu wants to ship important software (like Chromium) as Snaps, you really need to fix both of those things, because right now it's nearly unacceptably slow (even on a beefy system with NVMe Flash/8 Cores/32GiB RAM). Using EROFS would also work, but since that is not available in the current Ubuntu kernel that is unlikely to happen.