In Chromium it's generally runaway memory hogging tabs. Facebook is generally awful for example. Leave any Facebook page open all day (background of course, pos

In Chromium it's generally runaway memory hogging tabs. Facebook is generally awful for example. Leave any Facebook page open all day (background of course, possibly on another virtual desktop) and you'll be staring at a multi-GB tab by evening. I'm not sure what's causing the CPU utilisation in Firefox. It's common to blame extensions in the FF community because there's no easy way to determine where the problem is.