This build contains a new implementation of NVIDIA's NVENC encoder in OBS using the new NVIDIA SDK as well as implementing some new performance improvements. Specifically, the main improvement in this build is that frames from OBS are no longer sent to system RAM prior to being sent to the NVENC encoder -- instead, the frames are sent directly from VRAM, which should noticeably reduce resource usage.
This build is based on the NVENC improvements mentioned by NVIDIA at CES and in this article: https://www.nvidia.com/en-us/geforce/news/geforce-rtx-streaming/.
This will not only affect users with RTX cards, but the NVENC encoder in OBS in general.
The quality improvements you may have been hearing about will largely only be seen on Turing GPUs (RTX 20XX), but the performance improvements should be measurable on all GPUs that have NVENC (GTX 6XX and higher).
Full release of this version is scheduled to debut at the end of January, according to NVIDIA.
Edit 2: Added "Current GTX GPUs" quote.
Edit 3: Replaced the previous quote with a more accurate one from the OBS team.