Hello Yves,
AxCrypt works by decrypting files temporarily and then launching the appropriate application for the decrypted file, which thus is entirely unaware of AxCrypt.
Creating temporary files will take a while based on the file size and user’s system configuration. For example: If the file size is 200MB or more, then it will be opened in another few minutes. It will take more or less similar time of when we copy the same sized file from one location to another.
AxCrypt monitors the system for the launched app to exit, and when it detects this it will re-encrypt the file and wipe (overwrite) the decrypted file and then delete it.
If you have a good system configuration, then please write a mail to support@axcrypt.net with detailed report. Please follow the detailed instructions here to take the complete error report: https://forum.axcrypt.net/blog/send-complete-error-report/ .