Before the release of the Pentium CPU, it was common for game authors to do
as much as possible with integer math. With the Pentium, the floating point
math co-processor became a built-in feature, and by interleaving integer and
floating-point operations your game would actually go faster than it would
with purely integer math. The common practice on desktop systems is to use
floating point freely.
Unfortunately, embedded processors frequently do not have hardware floating
point support, so all operations on "float" and "double" are performed in
software. Some basic floating point operations can take on the order of a
millisecond to complete.
Also, even for integers, some chips have hardware multiply but lack
hardware divide. In such cases, integer division and modulus operations are
performed in software — something to think about if you're designing a
hash table or doing lots of math.