I once tried to make something similar, I used OpenCL for performance. But either my knowledge wasn't sufficient or the architecture wasn't properly designed, s

I once tried to make something similar, I used OpenCL for performance. But either my knowledge wasn't sufficient or the architecture wasn't properly designed, so on complex node trees the performance was pretty bad; if I remember correctly - because there was too much data being copied between RAM and VRAM back and forth and the engine was designed to be too flexible (for example, an arbitrary number of color channels) it harmed the performance. Eventually my enthusiasm faded and I abandoned the project. The original idea was to replicate Foundry Nuke's flow. Back then it supported GPU only for some of the operators.