Yep, that is generally what Windows does, using available memory for the disk cache. In the user trace the system had lots of disk cache (available memory) and

Yep, that is generally what Windows does, using available memory for the disk cache. In the user trace the system had lots of disk cache (available memory) and lots of _free_ memory, so there really was zero value in trimming the working set. But, (undocumented) rules gotta be followed, so trim the working set it is.