SUMMARY I don't want to report a bug, but share what I've lately experienced. I have a laptop to which I plug in external monitor. Built-in display has 144 Hz refresh rate and the external one has 120 Hz although via HDMI it works only up to 60 Hz. I have Lenovo Legion 5i with RTX 2060 and integrated Intel GPU. I believe I'm not the only one who experiences some stuttering while the external display is connected. I got used to it, however, a few days ago I have turned on my laptop without power plugged in and without HDMI plugged in. I've logged into my account and then plugged in power and HDMI. Now the internal display looks much smoother and the stuttering is a lot less noticeable. When I boot my laptop and log in with external display connected, the stuttering is noticeable again and the internal display is a lot more choppy. STEPS TO REPRODUCE 1. Boot the laptop without power and with external display disconnected 2. Log in 3. Connect power and external display OBSERVED RESULT Only by following the steps the internal display is smooth. When booting and logging in with power and external display connected, everything is choppy. EXPECTED RESULT It shouldn't matter if I boot with external monitor plugged in or not SOFTWARE/OS VERSIONS Linux: Manjaro KDE Plasma Version: 5.22.5 KDE Frameworks Version: 5.86.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION I'm using X11 with nvidia drivers and optimus-manager.
Mixed refresh is not possible under X11