The fix for #103803 , flutter/engine#35276 improves performance compared to software rendering, but compared to mobile or desktop it leaves a lot on the table. Reading back the pixels through the CPU is a high latency operation that can stall rendering for multiple milliseconds even on very fast computers. For example, on my gaming desktop PC, this takes anywhere from 5-10ms.

This is a particularly troublesome regression, because most of the interesting usage of shaders involve re-sampling some part of the child widgets using toImage. On mobile/desktop this operation is nearly free as we're simply manipulating a texture that already exists (or will exist) on the GPU.