Also I believe the traditional drawing algorithm (e.g. the painters algorithm) is not well suited for parallelization and how gpus do work. So the gpu is “fast” at slapping a circle texture on a couple of triangles, but rendering a circle from vector data not so much.

I think Apple has said that Core Animation (and maybe Core Graphics) now use Metal where possible, but vector to bitmap rendering is still done on the cpu.

https://raphlinus.github.io/rust/graphics/gpu/2019/05/08/mod...