Hi,
After asking to other people, this 40 should have greatly improved the multithreaded performances. You might want to try again with a build from master as it was merged about a week ago.
Also since pytorch used to be only used from python, multithreading was not a thing (because of the GIL mostly). So this has been fairly recent work in the core of pytorch but it should get better very soon.
Also if you have a model that behaves particularly bad and you can make a simple reproducible example, we can take a look into it.