BuddyPress.org

Why would you change permalink structure?

Never start the custom permalink string with any of these %postname%, %category%, %tag%, or %author% because the performance reasons.

Otto said…

Firstly, it’s really not any better for SEO to have the category in there, or to have just the postname there by itself. And anybody who tells you differently is wrong. If you disagree with me, then no, I’m not interested in arguing this point with you; you’re just wrong, period, end of discussion.