interesting video. as he says, the update might allow the adobe software to use more cpu cores, rather than ryzen specific. cpu usage at 38-50% is using 3-4 of 8 cpu cores, while 76-88% cpu usage is using 6-7 of 8 cpu cores.
Bill Gehrke since you have an intel 8 core cpu, could you do some simple testing between an older version of premiere and the new update? like exporting a single 5 min clip without any fx in premiere and watching for average cpu % usage during the export, and perhaps the export times. it might also be good to test a few different media formats like h264 and dhxhr for the source and export.
If you're talking about the Spring (CC 2017.1) update, it actually speeded up the CPU-intensive MPEG2 DVD export performance (with MPE in software-only mode) regardless of the CPU. In my i7-7700 (non-K) PC, the result when down from around 500 seconds to around 460 seconds.
I have found the same speed-up with my i7-5960 @4.5GHz Premiere Pro 10.4 with many runs of the test got 266 seconds and with the Premiere Pro 11,0 I got 251 seconds BUT when I tested the newest 11.1 guess what the CPU intensive score dropped to 240 seconds. This correlated with your findings