User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20051111 Firefox/1.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20051111 Firefox/1.5 Since 1.5, Firefox automatically creates backup copies of the bookmarks file. There should be a variable such as browser.bookmarks.backup with a boolean value to toggle this option. Alternatively, an option in the GUI would be interesting. Reproducible: Always Steps to Reproduce: 1. Open Firefox 2. Add a bookmark 3. Close Firefox 4. Repeat the next day 5. Have a look at folder "bookmarkbackups" 6. It is populated with files

I see only 5 files = 6 MB. A simple batchfile could also delete them as often as you want.

See Bug 307135

*** This bug has been marked as a duplicate of 307135 ***