Swarms do drain energy quite heavily, but for a powerplant like that in a cl10 wep fighter, you can fire pretty much the whole time you can see the enemy fighter without fear of "overheating", even when coupled with firing a full weapon load-out (apart from codenames I think, they'd eat your whole energy bar alone).
Perhaps it should drain energy even more then? The downside to this is (as several people have already said) it would no longer be a real "swarm", though it would still be very effective in short bursts.