So I tested my turrets out, as far as I can tell they're not causing much lag anymore, even the 100k+ mass ones! Provided that they don't collide with other turrets, of course.
With all the turrets firing at once (2 giant, 12 medium, 34 point defense) AND the entire ship loaded in I drop to around 15 fps. However, I think that's mostly due to the insane amount of cannon projectiles and missiles I had loaded on screen and not the actual turret collisions. Oh, and 40 active docked reactors :p. Without the anti-missile turrets firing (and a lack of missiles on screen) I was getting around 30-40 fps.
So yea, a big fat +1 from keptick for this update. I'm definitely interested in knowing how the magic happened.