The other day when I was going to download that Lynstats addon that someone had notified me about, I decided I was also going to install CyCircled. Let me tell you what an improvement this was over using just standard Bartender. Is there anything in Bartender in how it displays your boxes that would possibly decrease the FPS? I am using the SimpleSquare (I believe) skin for Cycircled, and my FPS is notably better.
I refuse to believe it either. I thought I was seeing things, but again last night while playing it was the same thing, my game seemed to have been playing much better than I'm normally used to. I know that when I typically ran quest helper, that may slow things down since I'm not running on a top of the line system anymore, but after shutting that off, my game flows better than it used to before even using it. Of course the typical higher populated areas like Shattrath and Stormwind would always bog down my system, but even that wasn't as bad as it used to be in the past.