On Windows, there's that lowest priority task (Zero Page Allocator) whose sole purpose is to zero out the freed pages and add them to the available pages list.

On Windows, there's that lowest priority task (Zero Page Allocator) whose sole purpose is to zero out the freed pages and add them to the available pages list. This way, allocation tasks don't have to wait for zeroing. IIRC, Zero Page Allocator's priority was so low that it was even lower than the lowest priority available to Win32 API's.