Pre-3.9 :You go to the tools option of the toolbar then to the Add-ons section and the loaded add-ons are there under the extensions window.
Post-3.9
It has it's own button.
Mozilla Firefox have many addons, you can find alot of them on their site.
try entering firefox safe mode and check disable addons
You can find Google Translate directly in the related link. You can also find it in Google Toolbar, Google Shortcuts Addons installed in Mozilla Firefox.
Hide Caption, exactly addons you need !
Go to Firefox.com, click Addons, and in the sidebar click Plugins.
Type 'addons' from the URL (Address) Bar. You should find the link 'Themes' from the left hand side. Choose a theme and install it.
The browser using the most memory is firefox. But it depends upon the number of addons and plugins used along with it. Chrome with 10 extension takes alot more ram than firefox running without addons.
open firefox, click on tools, click on addons, click on the addon you want to remove and click on Uninstall on the bottom right corner.
Getting Rid of toolbars can be a pain, but there is a simple addon for modzilla firefox, which will help to remove and prevent future addons,
on google chrome or firefox you can easily do it. get Ad Blocker plus from the chrome webstore(its free) and on firefox get Ad blocker plus from the addons( its also free)
I would try disabling some addons you may have installed. Gmail works perfectly fine with a clean Firefox install, so it's probably a third-party problem.
Compared to other web browsers Mozilla Firefox is fast loading, taking less CPU and processing load. Good compatibility of addons and less crashing or hanging problems.