My 2010 iMac (check my signature) sometimes lags a bit when some other applications are running in the background. I am planning to get a RAM upgrade. Do any of the other 2010 quad-core iMac owners with 4GB ram lag? I am asking this because a few weeks ago, the glass of the iMac cracked and had to replace the glass at the Apple Store. No problems with LCD or anything else (as far as I know). The glass cracked because it hit the leg of my table while I was trying to orgranize my room. Could my iMac lag at times because of this? Could my hard drive be damaged by the impact? Or could it be because my iMac has 4GB of ram and I run like 5~10 programs running in the background? My iMac lags when I try to shut down the computer. It tries to close all the programs but its slow and takes up about like 30 seconds. I have to force quit all the programs before shutting down. Should I get the RAM upgrade and see the how much it improved?