This Video brings some perspective as to what is happening:
The issue currently is really quite simple. Ryzen 7 is essentially like two CPU's with 4 cores on each block connected to their own 8Mb of L3 cache and these two 'Compute Complexes' are then in turn interconnected via the 'infinity fabric'.
Essentially it is like a dual socket Xeon system in one chip. A NUMA (non uniform memory access) architecture. And windows has support for this, but because these cpu's are inside one chip, windows is treating it as an UMA (uniform memory access) SMP (Symmetric Multi Processing ) architecture instead of a NUMA one. This is where the problem begins. This means that windows does not know to treat the L3 cache as essentially two different caches leading to cache misses.
Once windows gets patched to use a NUMA scheduler for Ryzen it will get a lot better. Once games get updated to take advantage of NUMA architectures and 8 cores effectively it will be a whole different story. Currently it would be possible to get great performance by setting Process affinity on Ryzen to only 4 cores on one CCX Compute Complex within Ryzen, effectively cutting the cache in half, but avoiding cache misses.
Thanks to roybotnik for testing this
Essentially the scheduler is assigning threads randomly, so depending on which threads/cores your application happens to get launched the performance may randomly vary dramatically.
TLDR Likely meaning that ALL benchmarks done up to now are next to useless.