I own a 4-5 year old macbook pro laptop. Every since I upgraded to Yosemite the computer has become extremely slow and it is definitely under performing. What kinds of things can I do to improve the performance of this laptop? I have checked the Ram and it is adequate...2GB. Also, there is a lot of free space on the hard drive. I have looked on the internet to find out if other people are experiencing this problem and some of these folks are suggesting to down grade the OS to the previous operating system. What do you think?