MyBB Community Forums

I've recently started up a website and have used wordpress (on a hosted server not through wordpress.com) with the MyBB plugin installed. At the moment the forums are very slow with abnormally long page load times. as well as this I am having a fair bit of trouble on the administration side of things. a lot of button images are corrupt/broken. If I try to access page 2 of the users list or view it in "table view" i get the following error "You do not have sufficient permissions to access this page.". Lastly several of the forums members cannot gain access to forums when they should be able to.

Will upgrading to 1.6.8 fix any of these issues?