As the title says, go into SteamVR Settings >Video tab > check the Manual Override box and set the slider to 100%
Why?
For me, I noticed ZERO quality difference in game between 100% and 200% (which is what mine was 'automatically' set to by 'recommendation'), but I DID notice a massive performance difference. It clearly doesn't actually do anything useful in Elite: Dangerous, not sure why, could be the way the game is coded, could be the way SteamVR works.
Background:
I updated my GPU and CPU and was very very disappointed to find out that it made hardly any difference to the quality I could play Elite in. For other games, like Fallout 4, Space Engine and 2D games, the difference was night and day. For Elite, I could barely crank up the HMD Image Quality from 1.25x like I used to, to 1.5x and that was it. It was struggling on 1.5x. I mainly upgraded my computer FOR Elite, and to find the performance change so minuscule I was utterly disappointed.
I also noticed that SteamVR updated to 1.1.3 at the same time, with new settings like Motion Smoothing, and this new Auto-resolution thing, that can be manually overridden. I of course fiddled with them plenty, but I never considered turning that slider down. Mostly because I didn't really understand what it did, and it recommended setting it to "200%" for my GPU etc. So I left it there. I know what 200% super-sampled resolution looks like in Elite, and I certainly wasn't seeing that, so I just assumed it wasn't carrying over, or was being overridden for the game and not applying.
After reading it a bit closer today, I saw that it said that when you check the "Manually Override" box, it overrides all games. To do it for specific games, go to the Applications tab. So I thought, why not, let's turn it to 100%. Lo and behold, after booting up, I got all the performance I ever dreamed of with this GPU and CPU out of Elite. Able to crank up the HMD Image Quality to 2x and getting BETTER performance than I was with 1.5x only yesterday.
HOW ABOUT THAT! Remeber the key point, turning it from 200% to 100% made ZERO quality difference in game, but a MASSIVE performance difference. Try it 'n see! Leaving it in the Application tab at 100% gets overridden by SteamVR whether on manual override or not, so unfortunately this is the only way around it at time of writing!
So if you happen to have the above set of issues, I hope this helps.
