Lately I’ve seen my Chrome memory usage go through the roof while on the Google Reader site. 1.5G of memory is not uncommon. Finally tracked down this bug in the product forums: “Waiting for plusone.google.com” which pointed to the new Plus 1 buttons as the culprit, with the solution being to add this filter to your Adblock+ filter list:
plusone.google.com/u/0/_/+1/fastbutton