Openshot preview is slow and with no sound

OS Win10 64bit, InstallPath C:\Users\myuser\Programme\Openshot Openshot-Version 2.6.1 / libopenshot 0.2.7 / Build Date 2021-09-04 23:49

Hi,

the preview function is very slow. While I'm typing this, preview is running and made 3 seconds, while well a minute passed in real time. Re-installing did not solve the problem, I also downloaded it again. Of course, I've also tried several restarts both of the app and my laptop.

Best regards
Botfather