After bookmarking a page, Firefox shows jumping star animation, after seeing that, the user might check the new bookmark in the bookmarks menu he just added, which they won’t see immediately in the unsorted bookmarks, to address this, Firefox 49 shows last 5 bookmarks in reverse chronological order in the bookmark menu. This makes the menu taller than that used to be in Firefox 48. If you want, you can remove or hide Recently Bookmarked smart folder, here is how.

Firefox 49 Recently bookmarked items

READ: How to get deleted “Most Visited” bookmark Folder back on Firefox Bookmarks Toolbar

Remove or delete recent bookmarks in the bookmarks menu in Firefox 49

  1. Click on the bookmarks menu icon, hover mouse pointer over ‘Show all bookmarks’
  2. Right click on it and select ‘Hide Recently Bookmarked

select Hide Recently bookmarked

3. Done. The bookmarks menu now will be compact and tiny as before. To show them again, after following step 1, you need to select ‘Show Recently Bookmarked in step 2.

UPDATE: Or visit about:config, find the preference browser.bookmarks.showRecentlyBookmarked and change its value false.