Performance: Extra long delay when browsing file manager

### Problem description

Config: linux debian + FreeCad.appImage 1.0.0

Whenever I try to open a file, to save on, to export into stl or import ...
whenever freecad has to rely on FileManager ... it takes forever to open the window, to charge the directory content ...
also, some directory names are missing or badly written.

### Workbench affected?

None

### Steps to reproduce

1. Create object
2. save it on disk

### Expected behavior

Takes for ever. Tooooooooo looooong.

### Actual behavior

I did start with version 1.0.0 I had no problem with version 0.?

### Development version About Info (in Safe Mode)

```shell
Have a good day.
```

### Last known good version (optional)

```shell
Version 0.?
```