[firebase_remote_config] Fetch is slow on first startup

[dev-tatsuya]

There is an app that uses RemoteConfig to A/B test the screen that is displayed when the app is launched for the first time.
When I installed this app on a device (emulator) that had never been installed, it took about 1 minute and 30 seconds to start.
When I debugged it, I found that it took about 1 minute and 30 seconds to fetch the RemoteConfig.
Indeed, this article states that fetching RemoteConfig for A/B testing takes time.
However, I think an app that takes 1 minute and 30 seconds to start up for the first time is way too long. We are concerned about user withdrawal.
So, as posted, how can I use RemoteConfig to A/B test the screen that is displayed at first startup so that the app opens quickly on first startup?
The code flow is to await the RemoteConfig fetch before runApp and pass the obtained value to the Widget inside runApp.

The version is below.

  firebase_remote_config: ^4.2.4

Thank you for your help.