I don't do video editing (aside from kids' birthday videos, etc.). I use mainly business apps and use Photos, but nothing really too GPU demanding.
In that context, my LG 6K feels no different in speed than my old 4K+ 3840x2560 monitor. Everything is fast on my M4 non-Pro with 24 GB RAM. The LG is a Thunderbolt 5 monitor, but I'm using Thunderbolt 4, as my M4 doesn't support TB 5. Because DSC is supported, I get 6K 6144x3456 at 10-bit with full 4:4:4 chroma support.