Set the drive up for the right current and you should be all set. Given that steppers can get extremely hot and still be within their temperature rise specs. You would need a temperature probe of some sort to know for sure if you have a problem.
Your reference to lag isn’t really the detailed description we need. Either you are loosing steps or you aren’t. If you are loosing steps there are many possible issues. Steppers don’t really lag they either mis steps or stay in sync. A servo can lag resulting in excessive following error but that is entirely different than missing steps.