High CPU by Firefox
You can make calls synchronous by starting firefox with
firefox --sync. This means firefox processes have to wait for others to finish.there are plugins that reduce the amount of stuff firefox has to load, e.g. adblock plus, flashblock and disconnect. If you're willing to deal with the inconvenience you can even use no-script (stops scripts from running except from whitelisted domains). No-script is a hassle but it can really reduce the load on your system.