Phpstorm on mac seems to be constantly indexing or lagging.. high cpu activity..

Phpstorm on Mac seems to be constantly indexing or something.  It's using a high amount of CPU pretty much constantly and can often go off into the weeds and take 20 to 30 seconds to respond to key presses..

Quite often I have to kill the process and restart the program to get it back to the point where I can use it..  This is quite frustrating..

What would cause this sort of behavior and how can I help you guys to track down the problem and fix it?

Thanks.