It's a bit like this fella....
A CPU without an FPU can not do Floating Point Instructions.
FPU's can accurately compute addition, subtraction, multiplication, division, and square roots.
They are specifically designed to compute Floating Point Numbers & off-load the CPU from having to do these Intensive calculations.
So yeah, if a Program can use one, it will be significantly faster than a CPU without one.
Try Ray Tracing an Image without an FPU & see how much longer it takes.