Hi, I am thinking of buying a MBA or MBP in the next months and would like to know which one would be best for my computing needs. The only tasks where I see my actual 2009 MBP lagging is dealing with large, image heavy PDFs. I am not sure if I should aim for CPU, GPU, RAM, or which combination of them. So, could you tell me what should I look in a computer to be able to deal with 4-5 big PDF files with no lag? Thanks!