My Battle.net App has been working slowly for months, it’s a 5-6s delay that happens any time I request app to make any action. Changing tabs, click on “Play” button, on Settings menu took me around 5-6 seconds to execute. It seems to happen to Win7 x64 users.
The solution: go to Control Panel -> Internet Settings -> Connections Tab -> LAN Settings button and disable “Automatically detect settings” checkbox.
It worked perfectly to me Recommend Support Team to write a troubleshooting article about this issue.