In general, recent consumer x86 CPUs will be faster at floating point code than fixed point code. Floating point multiply is already faster than integer multipl

In general, recent consumer x86 CPUs will be faster at floating point code than fixed point code. Floating point multiply is already faster than integer multiply; fixed point has the additional cost of the bitshift. (which is very small, but non-zero) Addition/subtraction are similar. Mid-range smartphones will generally have acceptable floating point units, and you should stick to floating point math. If you're targeting low end smartphones, you never know what you're going to get. Fixed point is generally only still useful on embedded. If you're building software for fixed point, it's generally because you know exactly what CPU your software is going to run on, and you know it doesn't have a FPU.