Ever since the Anniversary Update, I have been experiencing very slow user changes between different accounts. Prior to the update it took 2-3 seconds. Now, when I attempt to switch between different user accounts that are logged in, I timed it at about 18 seconds. During that time, windows is just displaying a black screen.

This may seem like a minor issue to some, but it is very frustrating. I have an HP Spectre X360 and one of the main reasons I paid more for a higher end laptop with an SSD was to be able to perform routine operations with minimal latency.

Does anyone have any insight into this problem?

More generally, how could I go about optimizing my system for fast user account switching? There is lots of advice out there on how to decrease boot time, but I have seen little on how to speed up user switching.