Have you tried removing GPU acceleration of your timeline to see its effects. Maybe a second GPU is in order to speed up the Warp Stabilization.
The GPU acceleration is turned on, I'll turn it off and see how much of a difference it makes.
Regarding a second GPU, I was considering upgrading to a 980 and keep the 970 as a spare, but your suggestion is now under consideration.
Just checking the settings I noted the Cache's were still going to a slower SSD, which have now been changed to be with the working files.
Also, I had disabled the GPU's PhysX, which now is re-enabled.
FYI, as noted I use this Video primarily to check the system stability and speed, and realize it is not a very scientific way to do this as is your method, which I will redo shortly. As well, regarding stabilization whenever it is required now I transcode it to a new video file and the problem of having to re-render the entire video no longer exists.
A couple of additional points; due to a serious crash a few weeks ago after upgrading both NVIDIA and Java software I've been reluctant to upgrade said software, but will do so shortly. Also, Speccy gets uninstalled with every major upgrade of Windows 10, so it's only being activated when I'll submit your benchmark.
One more point, regarding the DDR4 memory latency in this system is very slow, are you finding this to be the same on your system? Also, I'm considering of strategically placing a small fan near the SSD 950 including a temperature sensor, any suggestion on where to put the sensor?
With the GPU Acceleration turned off it renders in 16 minutes and 5 seconds.
Note; with the latest update to PR and the changes noted in my previous reply, re-running the renderings with the GPU Acceleration turned on it rendered in 7 minutes and 11 seconds.
Update - after placing the System Swapping file on Samsung's SSD 950 and removing it from another SSD drive leaving only a minimum size on C drive, the Rendering speed improved by 3.5%.
Also, there is a revised version of Speccy, which hopefully will be more friendly to Win 10.