Question / Help Game lags when there's a video open on second monitor

[NFSBloody]

Fortnite/League of Legends start lagging when there's a video(playlist) playing on my second monitor while streaming or if i have my StreamLabsOBS open. My only work around is to have nothing open there but i can't read chat.

 

[BK-Morpheus]

Do you have mixed refreshrates (144Hz+60Hz for example)?
If so:
Point 5: https://obsproject.com/forum/threads/common-mistakes-and-how-to-avoid-them.78116/
and some more:
https://forums.geforce.com/default/...a-144hz-monitor-if-you-run-windows-10-nvidia/