Where is most of the storage? Open Properties of the following folders and find out (you need to view hidden items in ''Windows Explorer→View'' to access ''AppData''). For me (Win 8.1, used for 5+ years), the distribution is as follows: * ''C:\Users\[USERNAME]\AppData\Roaming\Mozilla\'' (mainly profile data & crash reports): '''643 MB''' * ''C:\Users\[USERNAME]\AppData\Local\Mozilla\'' (mainly temporary web cache): '''1.09 GB''' * ''C:\Program Files\Mozilla Firefox'' (mainly the program's executable): '''207 MB''' None of those seem like much for a modern browser. I have barely used Chromium over the past few years so I cannot compare to others.