safari web content gradually uses more memory on my machine until it's using 6gb of ram, and the rest of osx is using up almost all of the other ram so my system grinds to a halt. They claim that OSX is good at memory management and that safari only will use up as much memory as is avaliable. So if you do somthing else safari is supposed to instantly use less or some shit. Chrome gave me similar problems.
The best solution to your problem is quite easy. All you need is a usb memory stick. What you do is go to this site http://pearlinux.fr/download/
and follow the instructions.
If you do it correctly your macbook pro will essentially run like a new computer, and no one at the coffee shop will know it's an imposter.