U2718Q, Lenovo Legion Y720, FPS drops

Hello,

I just recently got a Dell U2718Q 27" and connected it to my laptop with a mDP cable. The U2718Q seems to work well, but I have been experiencing some random FPS drops on it right right away. I have a GTX 1060 6GB on my laptop, and I set up the Dell U2718Q as the main monitor extending it to the laptop one. I can't pinpoint the cause of these FPS drops, they're not very frequent but they are very annoying. All the drivers are up to date, both GPU and CPU. I have down scaled the U2718Q resolution to 1080p since I had tried to go 4k, but apparently my laptop and graphics card couldn't handle it.

I would be glad if anyone could help me, especially because I bought the U2718Q to work with 3D graphics, so it is really important for me to work in a smooth way. 

I just tried to go 4k again and it doesn't seem to be too heavy for my hardware, but I still get these horrible FPS drops.

Updates = 

I still have to try to use a new mouse, but it almost looks like the mouse stuttering is decreasing. I tried to shut down the "Desktop Window Manager" in the task manager following a YouTube video, and it looks like it got better. I am still monitoring the situation and I want to try to use another mouse. But the lag has indeed decreased quite a lot, especially if I have to compare it to yesterday: every 30 seconds or a bit more I had the cursor jumping from an area to another. I guess if it was a monitor issue it would have kept doing it the same way?

I have bought a new mouse, it is a 8200 dpi one, not wireless, and it's very accurate. Things seem to go smooth now with this setup on my main laptop.