Can someone think of a reason why this happens?

[Crusien]

Hello,

this is my first post here, I hope I get well-welcomed in the community, greetings to everybody!

So my first time posting here will obviously be asking for help for a problem that I have and have always had.
I usually use 2 monitors (the main monitor is 144hz OMEN by HP, the second one is a regular IIYAMA Blackhawk G-Master 60hz) because I tend to multi-task a lot:
Gaming on the main monitor, watching a video or a stream on my second one. Or stream myself and watch the chat on the second monitor.
So the game I have a problem with is League Of Legends. For multitasking fast - Borderless screen is the obvious choice but here comes the problem!
Putting the game in Borderless mode makes the game and the camera movement in-game ''lag'' a bit or maybe stutter. It's not really a problem but it's really annoying to the eye.
Configuring to Fullscreen mode makes the problem disappear but that makes my multitasking a lot harder. FPS stays on 144, doesn't drop at all but i still feel the little annoying jaggedness. I've googled a lot about this and I've still not found a solution!
Will appreciate any feedback from you guys!
PC Specs:
MOBO: AsRock x570 Phantom Gaming 4
CPU: AMD Ryzen 9 3900x
GPU: MSI RTX 2070 8GB
RAM: Kingston HyperX 16GB 2400MHz
HDD: Random 1TB hard disk, no idea (League is obviously downloaded here)
SSD: Samsung 120GB 

[flibberdipper]

My money is on League just not being a great game to run in borderless or maybe something about it just doesn't mesh well with having multiple monitors/differing refresh rates.

 

Something that might be worth taking a look at is disabling vsync in game (and maybe capping the FPS at 144 if you want). It'd introduce tearing but it very well could eliminate or at the very least alleviate some of the stutter. I've had to do that with Insurgency Sandstorm which, while not exactly a great example (and also limiting to 60FPS), absolutely did help with bad frame pacing and in my case even tearing.

[Crusien]

 

 

 

 

 

 

 

 

 

7

35 minutes ago, flibberdipper said:

 

 

30 minutes ago, flibberdipper said:

My money is on League just not being a great game to run in borderless or maybe something about it just doesn't mesh well with having multiple monitors/differing refresh rates.

 

Something that might be worth taking a look at is disabling vsync in game (and maybe capping the FPS at 144 if you want). It'd introduce tearing but it very well could eliminate or at the very least alleviate some of the stutter. I've had to do that with Insurgency Sandstorm which, while not exactly a great example (and also limiting to 60FPS), absolutely did help with bad frame pacing and in my case even tearing.

I appreciate the answer a lot! I've tried all of the solutions you suggested but I'm still at a dead end. The only thing I haven't tried yet is having both monitors at the same refresh rate (which I don't suspect at all anyway). But I'm going at the direction of thinking that League just isn't a well-adjusted game with the Borderless option. 
I'm still thinking there is something that I'm missing.