Performance: cold start of Files app is too slow

- Check also with slow servers
- compare with Android "benchmark": how fast do we need to be?

Start by reproducing the Files app cold start with a slow server, then compare the result with the Android benchmark mentioned in the issue. Establish how fast startup needs to be and record a baseline before identifying the relevant startup path. Done means the cold start meets the agreed target, including under slow-server conditions.

Written by the indexing model from the issue text.