Bug report: The latest version is unable to backup or restore large data sets

[nagyesta]

Describe the bug

After the changes of #781, multiple problems were noticed:

1. the backup performance becomes exponentially slower with the increase of the number of files from the data set.
2. the restore performance becomes exponentially slower with the increase of the number of files from the data set.
3. the backup stream is sometimes closed prematurely causing the backup to fail.

To reproduce

Steps to reproduce the behavior:

1. Use the app with a large data set
2. Observe how backup and restore performs

Expected behavior

The backup and restore should work and should have similar performance as earlier versions

Actual behavior

The performance is terrible for large data sets. Backup fails in some scenarios.

The command you used

N/A

A minimal project that can be used to reproduce the issue

N/A

Environment

• OS: Any
• Version: 1.6.0
• Java version: Any

Additional context

N/A