Hi friends, I bought MacBook Pro 13 inch mid 2012, processor 2.5 ghz intel core i5, 4gb Ram. This machine is very slow it takes few seconds to open application, few seconds to save a document. previously I was using MacBook Air mid 2013 with almost same configuration, only major differences is its SSD. My question is if I upgrade my Mac Pro to 8gb ram will it improve the speed significantly. If so can I buy ram online. Friends please suggest.