Wow.
Two million pageviews in less than nine days.
For the record, the largest UBB.classic instances have been in the 3 million per
month range.
chuckee, you have officially outgrown UBB.classic.
Turning off Recent Visitors will provide a good performance boost. You should also follow the other bits of advice that I gave in the topic Ron linked to - namely forcing a DaysPrune of all in all your forums. That will help increase cache hits, which will in turn help performance.
UBB.threads generally has all the features of UBB.classic. The next release, 6.5 (currently in public beta form), also includes a rebuilt control panel based on the UBB.classic one. (Due to 6.5 being a public beta, I would not advise moving to it - version 6.4 is just as functional, though the control panel isn't as pretty <img src="https://www.ubbcentral.com/boards/images/graemlins/wink.gif" alt="" /> . You can expect 6.5 final within the next month or so, though we have not set a date for it as of yet.)
Do keep in mind that UBB.threads is a completely different product. The front end user interface is simlar to, but not exactly like UBB.classic. Your users may not like it at first.
You should also consider the
Eve platform... and take a good, long look at the
Thrive service. However, for that level of traffic, you'd probably be looking at a dedicated server.