Кста, а что вообще делает этот Denormals are zero? Раз его хотят спидхаком сделать, то я так понимаю он какие-то красивости в играх отключает или что?
Denormals are those numbers close to 0 that cannot be represented with a float because they are too small. If you put "denormals are zero", everytime a function obtains a denormal it just puts it as a 0.
The speed boost, as refraction himself said, is because there are probably a lot of functions that in some games keep orbiting around 0 because the result is a denormal and not exactly 0. So, by putting the "denormals are zero" condition, those functions think it's a 0 and exit. Thus the speed increase...
As for why some games are broken.. uh.. who knows XD Ref said it's probably something broken elsewhere, that influences compatibility once you put "denormals are zero".