Comment by ricardobeat

Page load takes twice as long as Chrome, videos buffer more slowly, and memory usage grows much faster. After a dozen tabs it starts visibly lagging when you press play/pause, the exact same session works flawlessly in Chrome.

It doesn't seem to affect everyone equally. Pretending to be Chrome sometimes helps - not too long ago someone found a piece of code that introduced seconds of busy delay for any non-Chrome user agent.