weak/slow start after driving

Yes, if starter(solenoid) gets too much heat it could be that doesn't work properly, try to use heat shield or wrap your header primary tubes(if you have headers). Those are cheap and easy to try. Or if you have clockable starter, turn solenoid another position (away from heat sources).Or maybe you have bad/worn starter. There should be at least 1/2" between solenoid and heat sources. And good/heavy ground wire from battery to under the starter mounting bolt is good to be.