Jimaroid
Journeyman Pro
Another test. Does the same thing happen if using a different browser without any ad block or similar extensions and plugins enabled? Do the same tests using Edge and Chrome. Also try running Firefox in safe or troubleshoot mode - there’s a menu option somewhere to restart itself in that mode.
I also suspect the PC is throttling/constraining and likely it’s something dumb in software causing it rather than anything truely intensive. It’s not unheard of for Firefox etc. plugins to max out the CPU in a busy loop.
Lastly are you running either display in native 4K resolution? Drop the resolution and try running at 1080p instead.
Lastly last thought however! A “cheap” HDMI2.0 cable has caused me no end of grief like this in the past, but that’s the the last thing to try unless you’ve got a known good HDMI2.1 cable knocking about. It probably isn’t the cable but thinking it wasn’t the cable is exactly what caused me a lot of grief.
I know it’s a lot but the only way to diagnose is to methodically try different things and eliminate.
I also suspect the PC is throttling/constraining and likely it’s something dumb in software causing it rather than anything truely intensive. It’s not unheard of for Firefox etc. plugins to max out the CPU in a busy loop.
Lastly are you running either display in native 4K resolution? Drop the resolution and try running at 1080p instead.
Lastly last thought however! A “cheap” HDMI2.0 cable has caused me no end of grief like this in the past, but that’s the the last thing to try unless you’ve got a known good HDMI2.1 cable knocking about. It probably isn’t the cable but thinking it wasn’t the cable is exactly what caused me a lot of grief.
I know it’s a lot but the only way to diagnose is to methodically try different things and eliminate.