User Access Screen - Change the default of save and close screen

We are on the limit of 150 users to get this screen to open. When changing many users this creates a similar time out error as occurs when more than 150 users are allocated. It would help to not have to wait for the screen to re-open after you have clicked on close. At present the only way to update a large number of users is to do some, save and close the screen and then wait for it to reopen again.