If you've been around on the "Interwebz" as long as I have (from the beginning...hell, I was on CompuServ in the early 80's) then you no doubt have a large collection of bookmarked pages that you've been carrying forward over the years. You probably saved them from prior computers, and you definitely kept them as you upgraded to later versions of Internet Explorer. And, if you switched to Firefox like I did, probably the first thing you did after installing it was accept the "yes" when it asked you if you wanted to transfer over those bookmarks. And those bookmarks are probably all organized in separate folders under separate topics, all ready for you just "in case" you ever needed them again.
But have you ever really needed them again? Go back and take a look at some of those bookmarks; do you even remember them? I'd wager a good quarter of them may not even be valid any more (do a search in there for GeoCities...) and when it comes right down to it, when you're looking for something on the Inerwebz I'm betting that instead of looking for old bookmarks the first thing you actually do is Google (or Bing, or wherever) the topic.
So - just maybe - it's time to make the break from those old saved bookmarks and "clean out the attic" of stuff you'll not ever use.
First and foremost, at least clean out the bookmarks that are no longer valid. There are plenty of free tools (search add-ins for Firefox) for you to download that will go through your bookmarks and give you a list of ones that just don't work any more. You can take that list and Google each one to see if it got moved to another domain, and/or maybe you can just post that link into the Internet Wayback Machine to get a neat sense of nostalgia. but once you've let that wave of nostalgia go past...delete that bookmark. Let it go, it's doing you no value. It's dead, Jim; let it go...
Second, you can simply browse through your lists and delete the ones that you bookmarked "just in case" but no longer need. That "How to make a Christmas Wreath with leftover rifle parts" may have been useful at the time, but not so any more, is it? (I made that up, but I'm willing to bank a beer that the site exists...) Just delete it.
Third, just look at the title of a link; does it make sense? Does it still sound interesting to you? If not, don't even select it, delete it. Do you even remember what it was about? No? Then just delete it.
Finally, avoid saving all those bookmarks in separate folders at all. Many/most of the ones I feel the need to save are temporary, things I want to use short-term. So, what I do is save them all on the main drop-down, so that the list becomes long and those old bookmarks eventually become annoying; at some point I no longer need them and off they go...
Yes, bookmarks take up almost no space on your computer, and yes, they don't affect performance. But what they do do is clutter up your life by actually crowding out the useful info; wheat from the chaff, and all that. Some links you just can't seem to let go, others just don't matter. Try deleting a bunch; once I cleaned out mine I think I actually felt a small sense of accomplishment... - GA