I must say that I, too, find the AI a bit annoying on frigates. As it has already been said, it behaves reasonably well in medium and large encounters, but in small ones it is way too passive in my opinion. Also, the AI's tendency to keep the distance in reverse until CR runs out is a bit aggravating, especially when there is only one enemy ship standing. It's clear victory is impossible, why doesn't it retreat ?
I think it should be a little more daring, and perhaps try more diverse tactics. For instance, a less-capable frigate could try for strafing passes instead of going for a head-on slugging match.