So it’s looking increasingly likely that nothing in the pop realm in 2011 will come close to topping the giddy highs of the Dr. Luke/Max Martin-produced “Till the World Ends” by Britney Spears. Sadly, she declined to perform that song on Jimmy Kimmel’s show last night (May 24), probably because she already did it for them a few months ago. But in its place we get another track from Femme Fatale, in the shape of the will.i.am cut “Big Fat Bass.” The best part about this performance is the stage set, with Britney flinging herself over some bulging speaker stacks throughout, which just about makes up for the lackluster electropop groove of the track.