Question Laptop for Gaming

[Nightwinq]

Hello I have a legion 5i lenovo laptop i've had for years and use it for gaming. I noticed that the other day when I was away from home playing Counter strike on just the laptop and a mouse no external monitor or keyboard on it was smooth, and felt really responsive. I play with an external keyboard, monitor etc plugged in and my laptop is at 240 hz while my monitor is 144. But after coming back and using my setup it made me realize that it felt less responsive and sometimes like theres an input delay. Is this normal? I was thinking its probably because of the hz difference or maybe the power supply of the laptop. I still get similar fps but it seems to drops sometimes on my usual setup and feels choppy.