Comment 96 for bug 1690719

I think the general lag / low FPS of some shell animations is not a huge problem. We've lived with that using X for many years. Just very short, hardly noticable UI freezes that we're all accustomed to. No need to throw out Javascript. ;-)

It only becomes very bad when using Wayland, because it reduces the mouse cursor FPS as well and makes the system very difficult to use in my case, as correctly targeting/approaching items on the screen is hard (AMD Phenom II 955 CPU and AMD HD7870 using Mesa drivers). I'm using the Ubuntu 17.10 default session, so not vanilla Gnome, but it should be the same issue (most reproducers described above work for me).

So I hope you're not trying to fix the general UI sluggishness of the Gnome shell first, which is only a slight annoyance and probably a huge work item. A solution that gives priority treatment to mouse cursor updates to always keep mouse cursor FPS at ~60 would probably solve most complaints people have and hopefully doesn't require big design/architecture changes. Until then, I'll use the X session. BTW, the Wayland smoothness (when Gnome shell is not suffering from micro-freezes) is impressive!