Bloody hell, I just realized why my Mozilla Firebird 'Add to bookmarks' prompt has been taking so long to appear lately: the Imported IE Favorites folder contains 2000+ subfolders!

Now, I haven't used my IE favorites since last December or so; it's mostly empty except for some shortcuts to local folders for use in Explorer. Apparently, during the last install, Firebird 0.6.1 thought it would be a good idea to add those folders and all their subfolders to its bookmarks file. Wow.