For 4K (without an egpu) make sure you have at least 16GB of memory or it’ll be glitchy.
An ultra wide is probably less strain on the system as they’re essentially all low enough PPI that you don’t need to use macOS’ UI scaling.
Re Ploki's comment about speed of 4k editing:
Do you create proxy media when importing your 4k clips?
I have a 49" 5K2K Samsung and direct connected to the Mini it is usable but an eGPU makes it worth using.
The i7 mini and 32GB RAM.
at native 5k2k 120Hz running on an eGPU. Straight out of the mac mini HDMI port was pretty bad for this monitor.What resolution are you running? I have the 49" 5k2k monitor and I'm struggling to get decent clarity and scaling.