Added to

\bin\config\platform\pc
rendering.ini

[ResourceLoading/Decompression]
NumThreads=12

to be the same as the 3900 core count, and the city game is now playable.
The gameplay experience went from Geralt not going in the right direction in Novigrad, to be able to counter parry enemy attacks.

It's getting pretty tedious to reload save after moving anywhere inside Novigrad, and been wondering if there would be some garbage purge setting for automating that