Interesting. Yeah, vsync is a latency killer and it's disabled by default in `rx`. What software renderers are not so good at is drawing lots of pixels every frame, so for example panning a view with lots of images open, or zooming in and out of an image that covers the screen.

I'd expect these kinds of operations to be slow at high resolution without the help of the GPU. You could probably speed things up with SIMD and multi-threading, at the expense of implementation complexity.