I have a powerhouse desktop for heavy lifting but I want a personal portable station that is powerful enough for my girlfriend to use hooked up to an external display when she comes over and has graphic work to do. I was really excited about the Haswell 13" rMBP as it promised to be the perfect blend of portability and power. After a few trips the apple store I am disappointed. There is noticeable(to me) UI lag on all the 13" models I used in the store. When connected to the 27" cinema display it get even worse... to the point Photoshop takes 3 seconds to register a [TAB] UI change which should be instant and drawing simple vectors on a 150dpi canvas feels sluggish. On top of that, people are reporting lag when browsing the net which is pretty sad. Contrast this with all the people saying they see no UI lag at all makes this a hard decision. I now starting to consider the 15" rMBP and the MBA 13" which dont seem to share these issues and feel very snappy in comparison. Unfortunately, neither of these machine seems to be "the perfect blend of portability and power". Do any people here use the Haswell 13" rMBP for Adobe suit work and web development with an external display? Could the lag I keep experiencing on the 13 rMBP just be from the laptops running hot from being on all day?