When I had to replace my stolen surface pro 2 last year, I purchased a SP 1 as a stopgap until I got an SP3. Having 8GB of RAM in SP2, I was very concerned going down to 4GB would be noticeably different regarding performance. Its something I was paying very close attention to, but running it under normal conditions (PhotoShop , AVID, IE, metro apps opened) I did not notice a significant drop in performance at all. I think Windows 8.1 is very efficient with its memory usage, particularly with metro apps. In short, there aren't many useful reasons to fully close apps as Windows handles it very efficiently.