All builds have in common that the GCC compiler is used for building libavcodec, which is ffdshow's main library for decoding. This library contains a lot of hand-optimized assembly code (which auto-detects the CPU's supported feature and instruction sets). Using additional compiler optimizations or advanced instruction sets (such as SSE/SSE2) doesn't result in any significant or noticeable performance increases. So when comparing pure decoding performance, there is almost no difference between the builds.