As for editing video, it depends entirely on which program you use on which OS and system, if you are an Apple user then Premier Pro is slow, if you are using FCPX then you can scrub through anything easily. Heck I can easily edit 4k on my iPad if I use Luma Fusion, but I am not trying to force my workflow into a system that isn't optimized.
I can easily work 1DX MkII 4k in FCPX on my MBP but I have 32GB RAM, 6 cores and 2TB of internal SSD.
PP in Windows, FCPX in Apple, Luma Fusion in iPad OS, all work 4k effortlessly with modest processing power.