[mort96]

I'm not sure it seems like something you'd easily find through profiling? The change was changing a memory allocation to use GPU memory rather than system memory. Allocating system memory probably isn't noticeably slower than allocating GPU memory, so the line that's at fault wouldn't show up when profiling. Instead, memory access in GPU-side raytracing code is just a bit slower when accessing the allocated memory.

So you would have to profile GPU-side code, which is probably really hard; and you'd have to find slow memory accesses, not slow code or slow algorithms, which is even harder. And those memory accesses may be spread out, so that each instruction which uses the slow memory won't stand out; the effect may only be noticeable in aggregate.