I disabled it on the monitors themselves, they have the same manufacturer, but different sizes/models. I also disabled it in my AMD GPU settings. This appears to have solved the problem. I'll be keeping on WOW TBC Classic Gold the lookout for problems that may arise.
Original Post In the past, I've experienced flickering issues, I'd hesitate to ever call it full on studdering for the moment. It's a constant issue which really has made it extremely difficult to solve. It had reached the point that it was driving me mad and I decided to investigate what might be the reason.
Short story, it is only recently that Windows allowed multiple monitor refresh rates to be used In the past 13 years, Microsoft seems to have tackled a long-forgotten problem regarding how Windows handles multi-monitor resizable rates. Windows 10's Desktop Window Manager, (DWM) was a cause of frame-skips as well as staggers when multiple monitors had differing refresh rates. This issue is fixed by Windows 10's DWM 20H1, which has the ability to support hardware-accelerated GPU scheduling (WDDM 2.7). A Reddit user has shown this effect.
This problem caused me to switch between a 144hz main screen and a 60hz secondary display to one monitor with 144hz. This was due to the fact that I did not wish to change my system, and my 60hz monitor was due for an upgrade.
However, I did so by upgrading to cheap TBC Classic Gold a larger main screen. This meant that my GPU was now driving more pixels with a higher speed. My GPU, which seemed to work fine previously for an application as simple as Classic WoW but was now having to put in the work. It was simply not enough for the job.
