Sorry I'm new to macrumours hope i came to the right place...my iMac is about 4 or 5 years old never had any problems with it at all.. I installed yosemite new upgrade last night and scrolling has been lagging and just the whole cpu in general i'm just wondering what i did or what i can do to fix this ....maybe its time for a new one but i wanted to come here first thanks guys,,,,