What's causing such a huge server load?

[Digital Jedi]

But fundamentally, we're talking about your server's performance and it's ability to cope with things.

Migration is fairly straightforward, though it involves a couple of steps you may have never done before. But the manual explains it pretty simply. Basically, you back up your database using a SSH/Telnet program, download all your hard files, re-upload vBulletin files to the new server and reinstall, re-upload all your old hard files and restore your backup using the same SSH/Telnet program.