It seems something just went wrong here. All of a sudden simply running a Processing sketch takes up all cpu power.
Didn't touch Processing for a few days, noticed the problem in 1.2, tried 1.5 but that didn't help.
Now I think of it, I might have installed a Java upgrade Software Update (mac) suggested a few days ago..?
Java SE 6 1.6.0_24-b07-334