This last MBP I bought was a lemon - since 2011 I've had the display, RAM, HDD, logic board, battery, etc. replaced (none due to damage). Recently there was intermittent freezing/wouldn't start up - the genius bar couldn't find anything wrong or re-create the issue, but of course it immediately happened as soon as I returned home from 3+ days of testing. Ultimately they suggested it may be a corrupt version of OS Mavericks, so I just reinstalled it and crossing my fingers, it seems to be working again. However, processes seem to be slower than they should. I'm pleased that fans aren't running nearly as much with Mavericks, but am wondering what the bottle neck is. The typical tasks I find delays on is photo editing/data uploading/10-20 browser windows open running work - lags in switching photos/editing/expose. When I check activity monitor - it says there is no swap going on (and also 0 (0) swaps in/out when checked through the top utility in terminal). However, I'm consistently running 6.5+/8 GB - a typical activity monitor is attached (shows low pressure, but still high usage with little activity). Should I be concerned about this and would upgrading to 16 GB help with any of the lagging/delays? Or am I missing the issue completely? Thank you for any help and excuse the naivety.