When you just boot your laptop, and play the game, does it run well but then starts slowing down ? If so it may be cause of the heat, laptops fans are usually not that performant, try cleaning it from any dust in the inside, it's preferable that you only plug in the charger if the laptop is already at full charge so that it uses it as the main power supply, charging the laptop and playing games makes it reach a high level of heat, thus lowering its performance.
If the game starts in mediocre speed even when the laptop is in a cold temperature and not plugged in charge, that might have to do with some settings, First guess would be to update your Opengl drivers, are you using a save energy profile in your laptop? If so try using the standard profile.
If none of this helped, maybe upload your log and see if a staff member can assist you with your situation.
(NB; the game runs smoothly in Android sevices, maybe give it a try. )
Edit: Try also lowering sprites scaling, and the resolution, it will definitely help run it faster )