Why can't I just change the resolution to 720p without the game scaling my PC's screen with the border around it?
use that "resolution scale" option (bottom left in the Video Options). set the "fullscreen resolution" to your monitor's native res, and set the "resolution scale" to less than 100%. I'm not sure, but I think 720p should be around 50%, but it's not important since you can just look for whatever percentage gives you the visuals and performance you like
you should also be able to setup your gpu to automatically scale stuff. with nvidia cards, it's in the Nvidia Control Panel
but this beta doesn't run well for a lot of people, regardless of settings. so don't be surprised, or worry, if that doesn't help much
edit: I just messed with it, and it didn't do much for my fps, but it definitely made the game look like crap. cranking up it to 200% looked real nice but of course killed my fps
performance in this game really seems to have a lot to do with the server. I played a few full 64 player matches that honestly ran pretty well, and some that really didn't...