NLEs are not simply "players", they run A TON of their own processing load all the time. So simply comparing playback with a player and any NLE is not accurate.
What is the media, and what is your disc setup on that machine? Those are rather important here. For example, even a good machine that can play 1080p fine from say an internal spinning disk may have troubles maintaining playback with 4k clips from that disc, simply because sustained read/write will bog down after maybe 15-30 seconds.
Where are your cache/media cache database files stored ... hopefully on their own internal SSD?
Do you have a separate preferably SSD drive for media, especially if you're running 4k?
This is something I see discussions of every day on the pro colorist forums I'm also "on". People with pretty decent hardware trying to sort issues of playback, render/export and all that.
Basically with the load most NLEs put on a system, and the accompanying load that 4k and greater frame-size media applies to the system, SSD media drives or large striped RAID arrays are still often necessary.
So ... what's your media, your workflow & effects, and especially your system drive setup?