Digikam 9.1.0 App-Image lags after previewing 5-9 pictures?

Hi,

I switched to the current appimage from https://files.kde.org/digikam/

In preview mode (thumbnails on the top, preview of picture in the mail
area) my digikam freezes for several seconds when clicking through the
current album. For the first 7-9 everything is very fast but then there is
a massive lag.

My collection is very large but it is running on current hardware, database
on an ssd, a lot of main memory, etc.

I think i switched off all options that are suspect of causing such a lag,
i.e. background face detection, preview embedded, fast scan, ...

Best

Tonio (loving dk since the mid 2000er)