Adblock/noscript
"Interestingly, ad serving and web analytics services have a very high failure rate (shhhh), and of the 100,000 failures that Gomez is tracking a day, about 35,000 come from failed ads and 25,000 come from failed web analytics."
One of the major reasons I block all the third party crap is to prevent slowdowns of pages. Seems to work pretty well most of the time.