Import / Export system windows are responding too slowly

The issue occurs in my windows-OS, using the [latest] version (3.2.32000) of ganttproject.

When I go to:
File → Import → Spreadsheet → Browse
or
File → Export → Spreadsheet → Browse
The application stall for some seconds. (This is true regardless the Spreadsheet or other option)

Then a window open to select the file I want, or the location I want to save.
But every interaction with this window is very slow. For every click I have to wait a few seconds. It’s really annoying!

Can these “stalls” be fixed somehow?

File → Export → Spreadsheet → Browse

Did you mean Spreadsheet → Next? If not, can you please record a screencast showing the issue?

I noticed that pressing “Next” stalls for a while, but not Browse.