Playing at 4K with Supersampling at 2X...lol!! Or perhaps since you have your CPU and GPU overclocked, maybe you could have a throttling issue somewhere (if not the CPU or GPU, maybe the VRM's as I had in the past with a motherboard without proper heat dissipation for them) because of temperatures. "Is not happening in my other games" has nothing to do since games behave and use hardware in different ways judging by my own experience, I had throttling issues in The Witcher 3 and Fifa 16 after I got new hardware, but then in my other 200+ games no problem (Elite included), "undervolted" my CPU and solved the issue since VRM's won't get to the temp limit anymore.
You may think that by having enough money to buy the "best of the best" means that you'll run everything like a dream...well let me tell you that's not true in the world we live in sadly. It should be like that but is not.
There is more complexity in a graphics engine that you may think, aside from how the game or any game looks graphically speaking. Elite Dangerous is an always online game, there is data that is being transferred at all times, and multiple stuff going on in the background. The scale alone compared to "the other games you play without any FPS issues" is of no comparison at all. Most of those performance issues are caused by multiple factors compared to most of those games out there. Again, the open world aspect of it, the tons of calculations for the physics alone, AI's, data, information sent/transmitted/received while connected online, multiple players in the server/instance, etc.
I play in Solo like 99% of the time and I have a single stutter every time I drop into a new system in front of the start, and that's about it. Then the game has (as in any other game) a variable frame rate depending where you are or how heavy is the scene (from 200FPS in open space to 90FPS on planets) but gameplay is as smooth as it can get. No stutters, nothing that can make me rage as hard as you here.
Try to use Supersampling at 1X like a real gamer with common sense will do at 4K resolution (because you don't need that much of Anti Aliasing for that density in pixel count...) and perhaps some of those, for sure, minimal performance issues should go away.
Don't pretend you know more than other because you have better hardware. Money won't make you smarter.