This has been a pretty big problem for awhile and Nvidia did finally acknowledge it a month ago but had no real updates for awhile. Today however they have released part 1 of 2 for the SteamVR stutter issue, part 2 is only if you are using a hardware monitoring software with SteamVR.
Hotfix: https://nvidia.custhelp.com/app/answers/detail/a_id/5152
Hotfix: https://nvidia.custhelp.com/app/answers/detail/a_id/5152