Our application is creating a new Windows user in answer to each request. In space of one year hundred of thousands of new users are being added and subsequently deleted. We noticed that after a while our servers start to slow down while logging on a new user. The delay occurs when Windows displays "Applying your personal setting" message, taking 25 seconds on a used server as opposed to 5 seconds it takes on a brand new machine. Each time a user logs on it logs on using a brand new user account. We cleaned up the registry of any residual entries left over while adding and deleting a users but it made no difference. Is there any way to correct this problem without having to reinstall the OS?
Creating a new user for each session help ensure separations of concerns at user level. We cannot store users accounts from one session to another because we far have too many clients. This was an architecure choice made long ago which worked rather well for us so far.