I'll just reiterate what is said later on. The API is documented. However this extremely important effect of calling the API is not. We called the API expecting lower I/O priority and lower CPU priority or something like that. We perhaps expected lower memory priority. Really the documentation should have spelled all of this out.

But in addition to this we got a problematic working-set cap which can absolutely destroy performance. That detail needs to be documented (and the rest of the behavior should be as well).