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On Thu, 16 Mar 2006 09:27:41 -0700, Framework Studios: Hugo <> wrote:

If it 'only' means the FPU computes things differently internally, why does Lua start crashing as soon as DX sets this flag to single-precision? :-)

I don't know why it crashes, and I don't want to start guessing here.. Still, floating point bugs can cause FPU exceptions, so it's not impossible that this causes a crash. And as far as I know, this flag really only changes the FPU control word...

A performance hit of 3.5% just for having some FPU flag in the correct state without even knowing if it actually really is used (SSE2) sounds like a very good reason not to use double-precision to me.

Don't forget that this 3.5% gain was measured in an ill formed test case. In real apps I doubt that you would see this much difference. Anyways, this is your call, if there's an easy fix, then good for you, but I would rather opt to just avoid all the trouble altogether. You never know when it's gonna pop up again in some form of mysterious bug...