Hello, after trying many times I was able to narrow down the problem.
If I remove all .rules and .things data, the group agregation works (changing the group status based on the members)
but as soon as I activate some things, the switching becomes slower and slower, Openhab takes several seconds to change the group status, the switch items themselves switch immediately. This can also be clearly seen in the console.
I have not yet been able to narrow the error down to certain things or bindings, this problem has so far occurred independently of the binding or thing.
Another important note: after a restart, the problem is fixed for a while (if only very few things are loaded) - with every minute the group aggregation slows down until it no longer works at some point. This error seems to have occurred elsewhere
See this post with very similar symptoms: