Hiya, I installed Mountain Lion on a Macbook 5.2 (mid 2009, 4GB RAM) which was previously running very snappily on on Snow Leopard. Now, my macbook seems to stall every now and then when using the UI / Finder. Opening a print dialog causes a few seconds stall. Likewise saving a file causes a few seconds pinwheel. Even opening a text file causes a couple of seconds spinning wheel. I have installed MenuMeters http://www.ragingmenace.com/software/menumeters/ to see if I am running out of memory or CPU power, but I have plenty of RAM space, and sometimes get the lag without CPU usage going above 25%. Any help? I'm considering wiping my disk and going for a clean reinstall of OSX ML but it's a major effort that I'd rather avoid - I have a large amount of data to bring over and apps to reinstall.