Hello Peter,
Thank you for your feedback.
As I can see in your screen record, there are too many WYSIWYG fields on an editing page, which could slow down the loading time because each field needs to be enqueued some script files: CSS and JS to work.
Can you please export your field group to a JSON file and share it here? I will try to reproduce the issue and report it to the development team.
Please follow the documentation https://docs.metabox.io/extensions/meta-box-builder/#export--import
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