Post became very slow the last few days

When I click POST, it takes a long time before the post is really gone.
If I click again because I have the impression that the first attempt was wrong, I get the message that I click to soon and have to wait XXX seconds.
What changed? It feels like my posts are first checked before they are added to ET.

I checked my internet connection: upload 185 Mbps and download 20 Mbps. Ping always below 50ms.
Opening ET and scrolling thru the threads goes as usual, so no delay.

 

OK, we will see the result.

Added 15 secs later:
We went from +20 secs back to below 2 secs.