Question full screen videos

[doublefas]

when i use resolution 1920x1080 every video online from youtube,netflix anything (tried 3 browsers ) when i full screen the video the whole pc lags but when i change the resolution to 3840x2160 and i full screen the videos is all good.

any ideas?

 

[rgd1101]

what the exact model of the gpu and monitor?

 

[doublefas]

what the exact model of the gpu and monitor?

amd ryze 7 2700x
monitor its an asus 27" 4k i can remember the model have it over 4 years now