impressive CPU offload and FPS boost from NVidia "nvenc" codec

As I just purchased an NVidia GeForce GTX 970, I installed the FFmpeg "nvenc" codec to see if I would gain any benefits from the hardware encoding acceleration on the card.  From the results, I think I did!

H264 encode
In the picture below, you can see that the H264 maxes out my CPU at 92% while I transcode a 2.7K GoPro video.  Also, final FPS of the encode is 23:

Now here is the encode using the Maxwell class CPU on the GTX 970.  CPU utilization is down to 15% and my FPS goes from 20 to 38!  Impressive!

Encoding Parameters
The params are be a bit different between the two, but I think they might be good enough for a comparison.

H264
ffmpeg -i GOPR0099.MP4 -profile:v high -preset medium -vcodec libx264 -acodec copy output2.mp4

NVenc
ffmpeg -i GOPR0099.MP4 -c:v nvenc -acodec copy nvenc.mp4

Update 12/14/22
Compare these parameters:
FFMPEG_PRESET="-c:v libx264 -f mp4 -pix_fmt yuv420p -profile:v baseline -preset slow "
FFMPEG_PRESET="-c:v h264_nvenc -f mp4 -pix_fmt yuv420p -preset p2 -tune hq -b:v 5M -bufsize 5M -maxrate 10M -qmin 0 -g 250 -bf 3 -b_ref_mode middle -temporal-aq 1 -rc-lookahead 20 -i_qfactor 0.75 -b_qfactor 1.1"

H264 encode is roughly 133 fps and takes twice as long. Notice the two tall CPU spikes.

Nvenc encode is roughly 327 fps and half the time of H264. The small CPU spikes on the right that are 1/2 the length of the tall ones.

Actual timing boost is impressive, from 44s to 14s

Regular libx264

real    0m44.101s
user    9m51.905s
sys    0m5.016s

H264_nvenc
frame= 5898 fps=417 q=22.0 size=  126976kB time=00:03:18.14 bitrate=5249.7kbits/s dup=1 drop=0 speed=  14x No more output streams to write to, finishing.

real    0m14.730s
user    1m27.067s
sys    0m1.804s

Of course, scaling functions need special tweaks to command line that I haven't figured out and interpolate commands are still extremely slow.

 Custom command used:
reset;/home/sodo/scripts/reviewCut/renderEdit.sh 20221105.ts 1 200 2 5 "Blump" E

Reference
https://developer.nvidia.com/nvidia-video-codec-sdk
https://trac.ffmpeg.org/wiki/HWAccelIntro
http://developer.download.nvidia.com/compute/redist/ffmpeg/1511-patch/FFMPEG-with-NVIDIA-Acceleration-on-Ubuntu_UG_v01.pdf
http://ubuntuforums.org/showthread.php?t=2265485
https://www.phoronix.com/scan.php?page=news_item&px=MTg0NTY