Comment by Agentlien

I work within game development. Mainly on graphics programming and performance. There's always a number of things I know would speed various systems up but that I don't have time to implement because there are so many bigger fires to put out.

Also, I have rewritten CPU implementations to run on the GPU before and it's often nontrivial. Sometimes even in seemingly straightforward cases. The architectures are very different, you only gain speed if you can properly parallelize the computations, and a lot of things which are trivial on the CPU becomes a real hassle on the GPU.