SUMMARY
The external display seems to suffer from serious stutters. The symptoms include the mouse, animations and some apps.
This bug might be related to 487670. Not sure if these are duplicates since the issue seems to spread more than just on the cursor. 

STEPS TO REPRODUCE
1. Acquire a laptop with a high-refresh built-in display and connect a lower-refresh external display to it.
2. Try to use the system

OBSERVED RESULT
Stutters in mouse movement, animations and apps on an external display

EXPECTED RESULT
Smooth experience

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
Kernel: 6.9.7-zen1-1-zen (64-bit)
KDE Plasma Version: 6.1.1
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.2

Nvidia drivers: nvidia-dkms 555.58-1

ADDITIONAL INFORMATION
- It seems the stutters increase with load
- Changing display configuration (changing refresh rates, turning off the main display) didn't seem to change anything
- Built-in display is 240 Hz, external display is 60 Hz (Neither of the displays supports adaptive sync)
- The graphics card I'm using is 3070 Mobile inside of a laptop
- Oddly enough, in my tests Doom 2016 (Lutris) and Black Mesa (Steam) didn't seem to have any stutters, whereas System Shock Enhanced Edition (Steam) had those stutters