I haven't played yet, downloading now, but with the skill revamp pretty near all of the forumulas have changed. It's possible that there was a reduction, but most reports I've heard said that people were getting a net gain in most categories when compared to the old system.
As long as it's a uniform reduction (if there's any at all) across all ships, I don't see the problem.
Me and a few friends have noticed our turn rates are not what they should be among other stats, will this be fixed or is it a permanent change we noticed the change last night.
Did you train up skills like Starship Impulse Thrusters and Starship Engine Performance?
Both will help with your turn rate (SIT much more than SEP).
That said, my Excelsior seems to turn just a little bit slower (just a little) than it did before S5 after training those skills. But that could just be my own perception and is not grounded in mathematical fact.
If I remember correctly I think when I did a comparison when we first could transfer a toon to tribble my turn rate had gone down by 1 or 2 degrees per second when all was said and done (14.xx or 15.xx to 13.xx).