I am on a Macbook that has Yosemite 10.10 on it. Ever since I upgraded to this OS, the laptop has been very slow. 60% of the time when clicking on something, it goes into search with the muti-color fan spending. Can I remove this OS and go back to Maverick, I have never backed up this laptop so if it is possibly a virus and I backed up not it wouldn't do any good. I think. Please give me some ideas of what to do. Thanks.