Look at the Advanced Options group and see what the cache limit setting is -- probably the default and a large # of MBs, and the cache amount has maxed out. Flush the cache entirely, set the limit to a smaller size (maybe 200Mb) and reboot -- see if the behavior improves by doing that.

Do you run CCleaner to empty out files? That is also a good step -- the registry cleaner component might be as well, but if you do choose to run it be VERY careful and read the description for each of the results it might find, then allow it to delete things which you are CERTAIN need to be removed.

If you have submitted crash reports then please post the IDs of one or more recent crash reports that have a "bp-" prefix:

• bp-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

You can find the Report ID of recent crash reports on the "Help > Troubleshooting Information" page (about:support).

• Click the "All Crash Reports" button on this page to open the about:crashes page and see all crash reports.

If necessary then you can open about: pages via the location/address bar.

See:

• http://kb.mozillazine.org/Mozilla_Crash_Reporter
• https://support.mozilla.org/kb/Mozilla+Crash+Reporter