I spent some time investigating the root cause. So, here what I found:
- Use PSO cahing
- On old android devices, you can spawn actors that have complex materials before loading the main levels and show a loading screen.(shipping build - hitches in the first run of level - Mobile Development - Unreal Engine Forums)
- Asset Management could be useful, but for some reason, it doesn’t work on Android.
Useful article - https://developer.oculus.com/blog/developer-perspective-improving-memory-usage-and-load-times-in-ue4/
Hope this helps someone 