Bump? This issue still occurs on Opera GX build 67.0.3575.87 on Windows 10 64bit. Running a vega64, ryzen 5 2600x, 16GB of RAM and the browser is installed on an SSD. Running a dual monitor setup like the OP. This issue severely hinders my enjoyment of the browser and seeing it still occur so many months after this initial post is worrisome to say the least.
So playing locally saved files (through the Windows media player AND through opera) does NOT cause lags. I can watch them without lagging. Right now playing YOUTUBE Videos works totally fine. I think Netflix is the problem. Netflix in Edge & Internet Explorer & Opera is causing laggs. Nothing else does.
So there is no Opera-specific problem, but one that affects all browsers equally in connection with Netflix.
Possibly, but this is only a speculation, these delays are due to Netflix checking the network traffic (periodically) for the possible use of VPNs . Since Netflix is not free, their customer service team should be interested in helping you with that issue.
The only driver I ever updated is BIOS and Graphics (today). Which drivers should I check aswell?
Especially with Windows 10 all drivers should be kept up to date, because the various operating system updates often entail far-reaching changes to which the drivers (for motherboard, sound card, printer, WLAN, Bluetooth devices, etc.) must be adapted. For security reasons, drivers that are up-to-date are also recommended.