Can someone tell me how much space does the Mac OS take on an rMBP? I was thinking about buying the 15inch version but it just doesn't look so nice as a rMBP13 so I have some questions: 1. is there a decrease in performance when we plug in an external monitor? 2. is the rMBP 13 coping with some games like fifa13 or some older games. 3. does putting it to the max resolution decrease performance? 4. is 300$ more worth to buy the 256 version? 5. does the early 2013 have the lg or samsung screen?