[Dave]

There are plenty of ways to make your forum "faster", it just depends on how far you want to go.
- For example you can cache complete pages with Varnish, which you should only do for guests.
- Upgrading to PHP 7 gives you a nice boost. (requires changes in vBulletin's core files)
- Optimize and compress all of your static files (CSS/JavaScript/images)
- Tweak your vBulletin settings (refer to the links posted by the other users)
- Minify HTML output

Then it also depends on where the server is located, if someone from America visits a forum in Russia then there's obviously an additional delay of at least 150-250ms between every request. If you only have visitors of a specific country then you should consider buying a server at that location.

There are still a bunch other of things you can do to "optimize" your forum, like I said it depends on how far you want to go.