Loving the add-ons...
Cool Iris.......................Brilliant
Cool Previews...............Used constantly.
Download Helper...........Gets video and music effortlessly.
Evernote. WebClipper....Essential for using Evernote.
Fire FM.......................Music while I surf.
Fox Clocks.................Time for different places in the tool bar.
I.E Tab.......................For the few pages only IE will view properly
Open Download...........Opens everything in your OS assigned programme.
Secure Login...............Never need to remember a password again.
Speed Dial...................For those constantly used sites.
Track me not...............Keep those annoying companies tracking your surfing.
Fox Tab......................3D view of all your open tabs you can scroll through quickly..
Gi!!!!.........................Disposable emails when required, Just one click.
Have some more that are used less frequently....I have tried with and without Add-ons and didn't notice any speed issues.
Basil......Add-ons simplify a lot of what you probably already do. They don't require any real learning. They are there as aids. Just download one at a time and get used to it then move on...Good luck.