We'll figure something out.  I agree that this could be annoying if it doesn't perform well.

Thanks Grady!

Thanks for working with us to get that simulated.  

We identified and fixed the issue in the codebase, which was related to large numbers of users that had mapi/ews and/or eas enabled.  With our fix, results went from an average 15 seconds to show the domains list in a similar dataset to under 100 milliseconds on our systems.  This will be included in our next build.

MUCH better guys! Loads nearly instantly! Thank you!