Oh, so the reduction in RAM usage is going to mean it's going to use my precious VRAM instead? No thanks.
I don't know about GPUI in particular, but it's possible to make GPU-based rendering use less VRAM by generating graphics with shaders on the fly instead of using pre-rendered sprites/bitmaps like it used to be done with CPU-based rendering (e.g. computed gradients and drop shadows, large text rendered straight from curves instead of a prerendered atlas)