A Rebel Icarus with nothing on it except a type III engine moves at about 6.4, and will occupy other fighters (Or any other ship which prioritizes fighters) pretty much indefinitely despite posing absolutely no threat whatsoever. They’re cheaper by far than any other fighter group, and each group can tie up more than one opposing squad. It’s a pain to keep them in tractor beam range, too, since a dogfight with opposing attack fighters will random walk around the battlefield.
This is hilarious to watch (Especially at 4x speed. Whee!), and it’s still beatable with enough tractor beams, but I think it would be much nicer if the AI gave weaponless ships the minimum possible target priority.