I recently used AdwCleaner to get rid of Sweetpacks which must have installed from some free app I downloaded. It was apparently causing noticeable Google search delays in Firefox. I had also lost the ability to print from Firefox to my Epson wireless printer, though my Brother laser worked fine connected via USB.
Apparently, Firefox could not call the Epson wireless print driver, and would just stall in the print quene.
Ran AdwCleaner, and it removed a large number of Sweetpacks entries from Firefox. Long story short, Google searches now fly in Firefox. And my wireless printing has been restored.
I do realize that you can manually disable or remove rogue entries in Firefox configuration files in about:config. But can be tedious and certain browser hijacks can insert registry entries that can download and reinstall missing components. AdwCleaner can clean these out with just two clicks.