Most of OS does not use FLOAT, but most of the programs that run on the OS that play sound and video use float, and most of this are ported from Linux, compiled with static linking.
I tell you right now, I'm not going to waste my time down grading software to support slow CPU's without FPU. Having to jump to math library, simple fmuls and fdivs, has overhead, jumps and branches have overhead, registers has to be put in stack, and restored, and return values has be set and so on, I think the math library idea from 90's was wacky idea to begin with. And is not a good direction to be going.
It's more likely be using more double floats in my programs, because its not good idea to mix and match int with float, because of overhead; a FPU while its integrated in CPU this days. Actually works as independent processor unit, there is no way to move a value from a CPU register into a FPU register without storing it on RAM, so makes more sense to write code for the FPU or write the code for CPU instructions. Do not do casting between float and int, or at least as little as possible.
With Doom3 PC vs MacPPC, I recall PowerPC has issues with register data movements between FPU and GPRs. PPC has to copy it back to main memory (cache). X86 CPUs can move register data between FPU, SSE and GPRs without hitting main memory.
