[tetromino_]

Cairo has only limited support for GPU acceleration and hasn't seen much development this decade. So users who care about performance have either switched away from Cairo entirely or are at least reducing its usage and are taking it out of the fast path.

[Asm2D]

GPU support was removed from Cairo, because it was slower than CPU rendering and nobody wanted to maintain it.

[tetromino_]

Cairo's OpenGL support was removed, but I thought Cairo's X11 backend still has GPU acceleration for a few operations through XRender (depending on your video driver).

[Asm2D]

That's true, Cairo still provides XRender backend. Not sure it's that usable though as I think nobody really focuses on improving XRender, so it's probably in the same state as Cairo itself.