Thank you for your response.
I tested all plugins and it seems that qTranslate X (https://www.ads-software.com/plugins/qtranslate-x/) causes these problems. Only after I activate this plugin Give freezes. Unfortunately, I can’t stop using this multilingual plugin now because all site falls to pieces as it is translated more or less to three languages.
Furthermore it seems that this plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
When we searched for multilingual plugin qTranslate seemed to fit our needs and wishes and is now used for longer than a year I believe.
So what should be my next step?
