I recently upgraded from the stock 8gb to 16gb because I was noticing processes starting to stutter and lag especially with multiple tabs open across firefox and chrome. I checked my activity monitor and noticed I was getting quite close to the used memory out of the 8gb available. The chrome/firefox helper processes were the biggest drain. Now, even after upgrading to 16gb I still see the memory used going up to and sometimes past 80% of what is available. Maybe it's naive of me to think it, but I just assumed memory consumption would be less? I notice an audio stutter as well when the memory gets stressed. Most of my usage is general surfing of the internet and streaming videos from the usual suspects netflix, hulu, youtube etc..