Noticed while working on T5478: Kleopatra: Performance problems decrypting and encrypting large Archives.
The Verify/Decrypt dialog is closed immediately after clicking Save although moving the decrypted archive from the temporary folder to the final destination folder may take quite some time. I noticed this when I deleted the destination folder after a test and then Kleopatra reported an error when copying the files.
To make the user aware that the operation is still running in the background we should show a progress dialog or keep the dialog open (showing a progress bar) until the operation is complete.