It frackin' hogs the CPU. Safari on the other hand seems to slowly leaks in to memory, but doesn't hog the CPU that much. The web developer plugin on firefox is a gem of a tool that keeps me coming back to use it from time to time. Wish they could fix the CPU hogging thing so I could use it as my main browser on my poor single core G4 processor.
Enough, whining. Back to coding..
-- wishing for a macbook pro...