How to find out what's slowing your Mac down

News10: Question: My Mac has plenty of memory, but in the last day it's slowed down so badly, it's like its own gears are starting to seize up.

Answer: I ran into this problem on my own iMac a couple of days after installing Apple's Mountain Lion release of OS X. A computer that had not shown prior signs of stress was taking way too long to switch from one program to another, with frequent pauses while its cursor turned into the dreaded "spinning beachball of death."

(Worse yet, this only happened after I'd written a thumbs-up review of this generally worthwhile update for another freelance client.)

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