vBulletin is very responsive. I'm glad you finally went to vBulletin, I will post here more now. On decent hardware it will serve your needs just fine.
I'm not sure what the last forum software was that you had (the ancient, original software) but they were unusable in some ways. The database timeouts when using the search function were a real killer.
This is nice, good job. If you ever need any tech help, I can assist. I manage several missions-critical servers for a multi-national electronics company at a 9 billion dollar manufacturing site.