That's fine.

I assume you mean XHTML validation. Validation checks on the codebase are run regularly. We also test all views with php debug on and even clean those warnings up.

I would welcome a PM listing the validation errors you have seen plus a note on which tool you used to check with.

As to speed – bbPress is always going to be faster but that is because it is designed specifically to be a simplistic, basic bb system with no real feature set. It s good at what it does. the others you mentioned are all standalone forums that do not have to work alongside the WP codebase and are therefore focused on being a forum. This is a WP plugin.

Is there any way to speed up the forums?  Do having too many wordpress plugins going slow this down?  I would like it to be as fast as vbulletin.  

Well we would all like it to be as 'fast as vbulletin' but there are lot's of things that will effect performance. vbulletin is a dedicated forum that doesn't have to live side by side with Wp and other plugins. That makes a big difference. Anyway – there are some performance notes on our wiki you may like to take into account.

And, of course, you can always come join in and help us out with coding.