I believe the software has to take advantage of the GPU. The `foot` terminal renders on the CPU instead of the GPU, but beats GPU-accelerated `alacritty` anyway due to other effiency hacks described on their Performance page:

https://codeberg.org/dnkl/foot/wiki/Performance

There are various ways to take advantage of the GPU -- the so-called GPU-accelerated terminals contain bespoke OpenGL programs ("shaders") to do rendering on the GPU. Here's an interesting way of doing it: https://tomscii.sig7.se/2020/11/How-Zutty-works

Hmm I think it's more the case that an application has to go out of its way to not render on the GPU. High level frameworks' basic rendering operations are, of course, always GPU accelerated. They'd be crazy not to be! It looks like Foot is rendering using CPU by talking directly to the compositor.

Specifically, kitty uses VRAM as a font rendering cache: https://sw.kovidgoyal.net/kitty/performance.html

Right... but doesn't every serious desktop GUI framework already do that? They aren't drawing every glyph every time from the original curves, and where else would they store video data than... the video RAM.