onAuthStateChanged takes 30 seconds to callback when network is 100% loss

[sengoontoh]

• Operating System version: Mac OS
• Browser version: Chrome v69
• Firebase SDK version: 5.5.1
• Firebase Product: auth

onAuthStateChanged call back is triggered only after 30 seconds, even though user is already logged in previously. To reproduce the issue, get a network link conditioner and set it up for 100% loss. Download quickstart-js/auth example and set a breakpoint in the handler. It takes 30 seconds to trigger.

Now if network is actually offline (instead of 100% loss), it triggers immediately.

This creates poor UX for our users who are already logged in but suffering from poor network connectivity.

[wooliet]

I am trying to improve performance for users who have extremely poor connections and have found the same issue.

If I have explicitly set auth to use local persistence, can the initial callback for onAuthStateChanged not happen immediately?