The current builds make speedy fighter builds way too powerful. A cheap, fast fighter, like the achilles hull with a level 1 engine and laser, can kill 5-10X their cost. The only real defense is speedy fighters escorting y our ships, or a massive number of slots dedicated to fighter defense (turrets and defensive lasers).
I think the problem is that the current builds confuse fighters and bombers. Fighters should be fast, and deadly versus bombers, but useless against frigates and cruisers. Bombers should be slower, but able to do significant damage to capital ships if they get close. Fighters should be a defense against bomber runs, not incredibly deadly mosquitos unto themselves.