UBB.threads PHP Forum Software Community Forums UBB.threads 6 Version 6 Support Upgrading from Classic....Should I?

On that question, YES. Swapping to the PHP and MySQL format will give you a considerable performance increase on a busy forum, and at least a decent increase on a smaller forum.

I used Classic years ago (early version), and have used Threads since version 2.x perl...and much prefer the PHP/MySQL version over perl/flatfile systems.