System feels very laggy and choppy, can't use nvidia gpu

Hello, I am a new linux user, I have debian installed on my laptop. I intended to use the OS as primary to learn about linux. However, the system kept feeling choppy, and lags a lot. For example, youtube videos stutter a lot even after they have loaded, and I had to reboot to windows to type this because it constantly kept hanging and then a certain character got typed 20 times. Even when playing csgo I am getting very low framerates. I have installed the latest nvidia non-free drivers and have bumblebee installed. I tried the optirun launch option, but still the game seems to be using my iGPU instead of nvidia.
Any help with this issue is most welcome, I don't want to give up on learning linux and go back to Windows.
My system specs are:
i5 8300H
8GB DDR4
Nvidia GTX 1050 Ti
Samsung 970 Evo 500 gb