Your advice is not bad, but you should definitely try ISPC before rewriting everything in assembly. I'm currently optimizing Cycles Raytracer (without implement

Your advice is not bad, but you should definitely try ISPC before rewriting everything in assembly. I'm currently optimizing Cycles Raytracer (without implementing an actual SIMD-packet raytracer), and I'm a little bit tired of avalanche effect in modern compilers too. The unusual thing about Cycles is that its code can be compiled by CUDA, OpenCL and normal C++ compilers. GPU and CPU architectures are very different, so SIMD optimization is not trivial at all. Simple operation reordering can lead to completely different stack map and performance drop by 10%. And you won't ever know about it, until you test with every supported compiler (i. e. gcc, clang and msvc).