ga is a slow algorithm. Most likely you have nonlinear constraints, which makes the algorithm even slower. If you do not have integer constraints, then I strongly suggest that you do not use ga, and instead give patternsearch a try. It, too, takes a lot of time with nonlinear constraints, but it is often much faster than ga. This assumes, of course, that your problem is nonsmooth.
If you have a nonsmooth problem with integer and nonlinear constraints, you have few solver choices. The only other choice is surrogateopt, which has its own overhead, but can sometimes be effective. And surrogateopt allows for checkpointing, which can be very helpful in long-running optimizations.
Alan Weiss
MATLAB mathematical toolbox documentation
