You'd probably have to resort to tweaking the settings yourself for better results, dipping to 40FPS during an intense 64 player match is nothing out of the extraordinary
Technically you could play around with the turbo clocks of the 2400 and bump it up by 400MHz
Sadly I can't find any gaming benchmarks with both CPUs to compare except for Crysis 2 and Mafia 2 from TomsHW
Much faster for Encryption but not necessarily games
The i5 2400 wouldn't be the problem here since it will definitely not be bottlenecking a 280x, either a driver or a game issue if the framerate is lower than others with the same GPU