It's not possible to go back to an old version, and it's not possible this one could have ANY effect on DL. If DL affects your performance (and if it does, it's NOT because GSX), just turn it off.
We might consider adding a way to turn off DL in GSX vehicles, so you might continue to keep it enabled on the rest of the sim but, before doing that, we would need some more reports and proof the vehicles have an impact on DL but, right now, you are the only one that reported this.