Are fractions more computationally "expensive" than whole numbers?
This link below compares all arithmetic operations between floating point and integer variables on various architectures and processors.

With the general conclusion drawn that additions and subtraction are roughly equal, the performance impact arises in multiplication and division operations; with integer being faster. (Except for x86-64 AVX and POWER8 AltiVec where it is faster in the former for floating point and equal in the latter.)

Integer and Floating-Point Arithmetic Speed vs Precision: http://nicolas.limare.net/pro/notes/2014/12/12_arit_speed/