"Report User" window takes too long to close, causing multiple reports

Every time someone uses the "report" button to send in a complaint about a user, image, etc, I get the report 2-5 times. I was testing to figure out why this is happening, and it's quite simple. The window takes a long time to close, and users think they haven't clicked yet, so they click Submit a bunch of times until it shows them the "thank you" screen.

Can you guys do something to either disable the Submit button once it's been clicked, or have the window respond faster?