6500 bookmarks? Do you use then like I do? Add a bookmark. Never look in bookmarks.
Assuming you do use them, how often do you visit 6500 websites? Seems like searching in general would be easier than searching through your bookmarks.
Do you run a script now and then to see if the site still exists?
Finally I cant tell you how curious I am what you bookmark for 6500 websites. Consider exporting them?