Windows 10: input lag, or 2nd monitor reduces the fps of the main

Two monitors: 1. Main 2k 144Hz 2. 1080p 60 hertz I have a problem in the form of an imputlag on the main monitor, that is, the picture is not smooth. When I turn on something on the second monitor, a browser, documents, archicad, obs, in general, any application. How is it worth transferring everything to the main monitor or minimizing it. That becomes a perfectly smooth picture. I have reinstalled the operating system, drivers, and more. Nothing helped. Come back win10 last. I am terribly uncomfortable playing because of this bug, please let me know how to fix it or there will

:)

 

Major input lag since the latest update playing Overwatch

A week ago I got a windows update. Since then I had my games FPS capped at 60 frames and experiencing enormous input, mouse/monitor latency. I turned off game mode and disabled fullscreen optimalization to remove the FPS cap but I still having major input
lag peaking at 335 ms lag. This has made be extremely frustrated. I tried updating my drivers and graphic card but nothing has fix this issue.

 

Reduced FPS on inactive game client

After switching to Windows 10, when I play a game using 2 game clients, the inactive client has a severely reduced FPS. Whichever client has focus would run well at expected FPS. The inactive client would reduce FPS and stutter until made active again.
I did not have this problem (on the same computer) when running Windows 8.1.

I'm running Intel I7-4790, 16GB RAM DDR3, and NVidia GEForce GT740.

I've experimented with the clients in Windowed vs Full Screen, on the same monitor, on separate monitors, et cetera. I've also had the same experience if I have one game client up and try to stream video from a browser or if I try to stream two videos from
separate browsers - the inactive client/browser has severely reduced FPS.

Any ideas?

 

monitor lags my laptop, adding delay for everything, except my mouse.

Hi! thanks for responding so quickly. It goes up to 60, but for some reason, will not allow me to choose 60, but 59. But that isn't much of a difference, anyway. so i dont think that is the problem. The monitor I am using is a Dell 2408 WFP, if that helps.
It was also fine when i plugged in my Nintendo switch, no input lag and no lag. I was also able to take an FPS test with a game. When i plugged in the monitor, i get lag, delay, and only 15-20 FPS. When i unplug it, i instantly get 60 FPS, and no lag, or delay.
Also, it used to work perfectly fine, i dont know why this started happening, it was completley fine before.