I use chrome anyway but there must be something wrong with the persons whose usage is 600mb with only 5 tabs.
I killed the Chrome application, then restarted. Again over a dozen chrome.exe processes were created totaling about 200MB. Now it's up to 350MB. It gets up to 1GB if I watch a lot of video. I assume Google is caching video in memory, just like Firefox.
IE 10 does seem more efficient in memory usage then Chrome.