You can try getting Logcat log from the phone. It's possible that you'll see some error message there which will explain the long loading time.
Are you using any external plugin like Enhance, analytics etc.? It may be trying to establish connection with its server at startup.
Just saw your other comments, it makes sense now - there are too many objects, layouts, event sheets. It takes time to read them all.
I have a pretty large game for Android, and the data.js file in the apk is only 700Kb.