Hi I have a 2010 Macbook Pro 2.8 Intel core duo with 4GB ram. I've recently upgraded to Yosemite 10.10.1..... When running games that used to run perfectly, things are slowing to a crawl. I have the graphics processor on, I have run disk utilities to verify and repair etc with no problems. When running the application, I switch to Activity monitor, its only using 47% of my CPU, and 850mb of memory - there's nothing else running thats significantly using other resources. Is this due to the OS update?....or could this be a deeper issue? If its the OS upgrade, is there a way to go back to the previous version? Any help would be very much appreciated!! Many thanks in advance for any help!