That's not good. I haven't really tested with lots of bookmarks myself though, just curious, how many bookmarks do you have?

In earlier versions of the add-on, i was grabbing/loading all the bookmarks on each time you wanted a random bookmark but because I don't have 1000s of bookmarks, it wasn't ever an issue for me until someone pointed out it takes a while.

So the latest version will cache all your bookmarks on load so it doesn't have to do that and firefox most likely stores that using temp data.

Do find it really weird that it is affecting windows explorer though. I personally haven't run into this.

Sorry for the inconvenience though.