Quote Originally Posted by nonoob View Post
What's actually faster in hardware is using 80-bit floats, which is native to the floating-point hardware internally.
On certain x86 hardware and OS combinations, maybe. Even on systems using x87 code, it could still depend on whether the code is FPU bound or memory bound. And even taking that into account, using 80 bit values instead of doubles could prevent the compiler from doing various optimizations.

As others have said, if it's running slow, profile your code. Don't just guess.