Explain why i get better fps when im using a monitor

[cowanplayz8164]

So i have a msi gs63vr laptop and it comes with a gtx 1060 and i have a 240hz monitor (because i want overkill) and im playing a game (ex: fortnite) and on my monitor i get better fps then my laptop screen and im not using the intrgrated graphics can anyone explain why?

 

[thtran6]

Your laptop screen is not capable of handling that high of a refresh rate and/or response time.
Most laptop screens aren't built with 240 Hz refresh rate anyway. So while your gtx 1060 is strong enough to spit out more frames, the screen probably can't handle it. But you external monitor can.