Wendell from Leve1Techs has done an investigation even further than some earlier ones.
Apparently the problem in performance may be somewhere in MickeySoft's thread scheduling.
With due deference to Mickeysoft, scheduling is actually kinda hairy, and in many cases architecture-specific, and the 2990WX does introduce some interesting architecture unexpectancies (normally, all cores would be connected directly to RAM), so the initial theories about some kind of problem in the Infinity Fabric was a likely suspect, but this makes it look like this is not the case, and instead that Mickeysoft needs to get their shizz together and do this right. Linux doesn't seem to have these issues to this degree. If Mickeysoft wants to retain their position, they need to step up to the plate with a home-run hitter. There are already MANY reasons to run Linux on a ripper, not the least of which being it's long-established performance advantage (wish FBSD would get serious about this again! what ever happened to the good old days when J. A__croft deemed FreeBSD to be a Communist Threat that could take over the West? (for real, he actually said this! according to the FEC, Gates told him to in order to prevent competition by way of a huge campaign donation!)).