How to increase the VM memory for IntelliJ IDEA

To increase the maximum "total heap size" the default value of 256 MiB, you have to modify the /Applications/dev/IntelliJ IDEA 9.0M1.app/Contents/Info.plist file under your Mac OS X. You have to change the VMOptions key:
-Xms64m -Xmx512m -XX:MaxPermSize=256m -Xbootclasspath/a:../lib/boot.jar -ea

...these settings should beware you from hangups during long working sessions.