On my site, the homepage, which runs outside of vBulletin but still connects to a database to fetch news from blog software, generates in about 0.01s. The forum, powered by vBulletin, however, is much slower in comparison. An empty page that simply includes global.php takes 0.05s to generate, and important pages such as the index and forumdisplay average 0.10 - 0.15s. I've seen showthread go up to as much as 0.20s with only 15 posts per page.
So, my question is, would performance be considerably better if I were to switch to xenforo? I'm under the impression that a lot of stuff under the hood in vB isn't as dynamic as it ought to be, and that use of caching is minimal (I've myself implemented memcached use for lots of stock features as well as mods).