Question Game runs slower on laptop screen than external monitor

[BinaryGreen]

I'm only using my laptop's screen to game on right now, and I'm getting lower fps than when I'm using my external monitor. In CSGO, I'm only getting ~90 FPS, when on my monitor I'd get ~280 FPS. Both screens are 1080p@144 hz, but the external monitor has gsync, though I don't think that would affect the actual FPS or performance.

I don't see why the game's not running at a higher speed as if my external monitor was plugged in, it should do no difference. Can anyone help?

 

[BinaryGreen]

I've just tested it on different games and I'm receiving lower framerates on them as well.

EDIT: I also think that this may have to do with Optimus, and the fact that nothing's directly plugged into the dedicated GPU?