By default SteamVR applies 1.4 super sampling, when set to 100% resolution scale. That might cause some people to think Oculus API has better performance.
For those with performance issues, even though frame time are good (below 11.1ms for Hz displays) and with hardware expected to be capable of running DR2, can try the following settings on a 1080Ti/ 2070 Super or better:
nVidia 436.15, forced 8x AF without AF optimization
SteamVR Beta 1.7.14, rendering resolution at 2016x2240, Async reprojection off (by hitting shift+a in VR view of SteamVR)*
2x AA, AF off
Select medium profile, change the following:
Chromatic aberration and light streaks: Replay
Lense dust: off
*This is a crucial setting, that was causing stuttering even though frame times were below 9ms, because reprojection constantly created synthesized frames without any actual need. Usually it will show you on screen if async reprojection is disabled, but it seems to be bugged in current SteamVR beta. However it should still show the current status in the lower left of SteamVR settings.
Do not disable async reprojection (and enable always-on reprojection in this way), if your computer is not capable of delivering the necessary Fps corresponding to your HMD's refresh rate. With this setting it is most important to leave your GPU some headroom (like 85%, don't load it to 100%) or you might see occasional stuttering.
Disclaimer: I have not tested these setting in all locations. Australia at night and Poland ran at about 9ms frame time. If I run into performance issues, I will probably disable AO or set ground cover to low.