We run it daily on about 10 macs in the office & are not seeing any issues. They all have at least 8gigs of RAM (most of them 16) & we have them using the latest JAVA by modifying the "JVMVersion" key in "/Applications/PhpStorm.app/Contents/Info.plist".
Did you use the latest Java that comes with Yosemite? Are you using a strong mac?