If you look on the Steam forum for this game you will see that lots of people have this problem. No one can figure out the issue but it didn't exist at launch. Something got updated either with SteamVr, the game, windows, or maybe video drivers but unfortunately it is very broken for alot of people.
One good fix is : Right click the game in your Steam library, then go to "properties" and "set launch options". Paste the following:
-novid -console -vconsole +vr_fidelity_level_auto 0 +vr_fidelity_level 3 +vr_render_scale 1.15
If that fixes your problem then you can increase the fidelity level
(fidelity_level 4, 5, etc... up to 8) up until performance suffers. This gives me perfect performance.
Another possible option is to go into the games settings and change the engine to Vulkan. Make sure and restart the game. People get mixed results with this.
Finally I would play with the motion smoothing options in SteamVR. You will definitely notice a difference, for better or worse.
