i play from pc almost always (and remote-in to pc when i'm mobile). some of the ads/tabs of utopia take up 2,000,000+ K memory, at least that's where it seems to plateau. usually they start at 300,000 k (normal memory usage) and then ratchet up and up and up until it hits 2,500,000 K or so. i always have task manager up so i can 'end' those tabs.
i can usually tell when it's happening cuz chrome shows the activity on the lower left of the window (e.g. what site is being called / what site chrome is "waiting" on). a tab that is on it's way to 2,500,000 K will constantly be calling random sites. a few times, while it's doing that, i've right-clicked and then click on "inspect" (chrome), and then look at the "Network" tab; hundreds of sites being called as fast as possible, 10-15 per second. it's really crazy. and random. but eventually any utopia tabs left open will do it if/when it refreshes ads enough times.
just my two cents. maybe this can help narrow down the offenders?
edit:
i just wanted to add that it's not just utopia tabs/ads that do this. i've seen the same thing with apnews.com and yahoo.com (yahoomail) and i think once with cnn.com