Ok, I am going to take back what I said earlier.
I have read all about the firmware upgrade and what it affects and it's purely for display port 1.3/1.4. There is nothing in it that's supposed to affect performance. It definitely shouldn't make any difference to VR, especially since I am using HDMI. But, it has, it's also made a difference in 2D gaming. I know, it goes against all logic and I can't explain it. Is it placebo? I would like to think it isn't, but anyway here are my findings.
My system, just in case it matters is an AMD Ryzen 1700, MSI X370 Pro Carbon, 16GB ram, 1080Ti, Asus MG279Q Freesync monitor, Oculus Rift.
The two things that I have tried are The Witcher 3 and Eleven: Table tennis in VR. Normally when I play Witcher 3 I get occasional drops in framerate, a little stutter every now and then. It was no big deal and I just presumed it was brief loading of textures or new areas. I played for 2 hours last night after the update, didn't stutter once. Smooth sailing all the way. I am not taking this as 100% proof of anything just yet, but, it was a remarkable coincidence.
Then I booted my VR headset and tried Eleven Table Tennis. When I had the core 2 home enabled I was getting random lag in the game. Again, sort of stuttering. Other people have had the same issue and it was easily solved, just remove the new dash and go back to the old one. So I enabled the new Dash and started the game. No flicker or lag or stutter for the hour tested it.
Am I getting a performance boost? I am not sure as I didn't measure frame rates. I don't think I am, but, the Firmware update has improved something.