http://bugs.winehq.org/show_bug.cgi?id=11674
--- Comment #139 from gpiez@web.de 2011-11-02 12:38:53 CDT --- I can at least answer the first part of your question: An working implementation of GetLogicalProcessorInformation does not affect the performance at all (at least on my box), where the whole patch gives a huge performance boost.
I tried it on my box, which has some more cores (AEs implementation returns a fixed dual core) with an fleshed out patch and it did not improve performance. The reason might be that wow runs on several threads, of which only one does really do something.
I think the reason that doing the rendering in an separate thread yields a performance boost is that you are essentially offloading the opengl->d3d overhead to an otherwise unused core. I admit this is based on pure speculation ;-)