I was wondering about the significance of the returned value 0.63739. Best explanation I found was this HN post [0]: "Referencing a US telephone keypad, it spells NERDY"
Test the API kernel calling convention when dealing with 64 bit IEE754 doubles on a 32 bit CPU, especially when dealing with MSB vs LSB processors.
Also, a long time ago (pre 486DX), processors did not have FPU circuitry instead it was a FPU coprocessor. When dealing with a kernel context switch, you'd have to copy all registers to a stack. With a coprocessor, you'd have to make sure those registers got copied as well. Which was slower with coprocessors ... So for a time some real time kernels did not allow context switching of FPU. To support that, you'd get the performance hit.
These days its all integrated so you dont have to worry about it ...