you could get "optimisations" such as
if (CPU.ID == Intel)
{
//run this codepath
}
else
{
//run this deliberately slower codepath
}
I don't really know Assembly, so I wouldn't know how exactly it might look there. But other people do and have identified codepaths where Intel's compilers deliberately made non-Intel CPU's run unnecessarily slower codepaths, even if the source code has no such thing.