Without even seeing your code the answer is: you're probably looking in the wrong place. The performance problem is not due to the use of floats, and switching to ints will not fix it.
As soon as you get performance problems (and even before) you must find ways to benchmark and measure the performance of your code. You might use profiling, or internal tracing, or some other way but you must do it.
Most performance problems are due to bad algorithms and/or a few small functions called millions of times. Fix the algorithms and recode the small critical functions and you will probably solve the problem. Switching your code to int is something you do after you've fixed everything else and need just a little more.
Put up some code on CodeReview and I'm sure you'll get lots more help with it.