Sorry I have several question relative to the same problem.
I am using Netbeans 6.8 on OSX 10.5.8 with java 1.6.0_17 and after about 5 minutes of work, the cpu usage
I found that version 7.3 (PHP build) comes with about 25 plugins, and I don't need all of them. I've been able to disable around seven of them, and CPU performance seems to die down much more quickly to idle levels now. So, if you are having CPU problems - with NB on any OS - this is probably worth a shot too.