We should be able to check for SSE2 support in the user's CPU with the installer for post 3.1.1 builds (current builds only have SSE enabled). Which is great, because I've noticed some more efficient combination of operations in the generated assembly with it enabled. We could enable AVX, but it is still relatively new (my main dev machine's CPU is circa 2010 and thus doesn't support it). Plus requires Win7 SP1+ IIRC. So yeah, that would kind of narrow our userbase.