Right when the missiles spawn from the turrets they face the wrong direction but then they turn and face forward.
No they do not, the continue to face about 5 degrees away from their target while flying straight towards it. The weapon firing in that picture is an AI MLRS guard post, but the same bug applies to all missiles. Instead of having the image axes aligned down the exact center of the rocket trail and the center of the projectile, one appears to be aligned down the right side of the smoke trail. This leads to an incorrect rotation of the image.
For some reason I am unable to insert a second quote, but the bug exists over all firing distances and performance is not an issue for me.
Oh, that is just a performance optimization; approximation of certain angles (like rotation angle for drawing) that don't "matter" as "much".
May not be that big of a deal in most fights, but when there are several thousands of projectiles on the screen flying around at once (which is very, very possible in AI War) that need to be updated each frame, this can start making a big difference.
Yes, GPUs could theoretically help with this (turning this from a decent cost to so trivial you could have much more being drawn at correct angles), but the devs want this game to run well even if you have nothing but a low end 2D accelerator, or possibly even no GPU.