Backend/Site unresponsive and loading super slowly after saving

Dear support

Please advise in my situation. Site details below in the private area.
I tried on different browsers and computers to change the background-color of the color section at the bottom of the page and I duplicate some elements in the section. After I publish, the site gets unresponsive. Even in a new tab it wont load. Sometimes this process finishes by luck and I am able to continue working.
If I open an incognito tab in parallel I will experience a super responsive site. If I repeat the steps there it will be unresponsive there too. Saving seems to trigger this behavior in the current browser instance.
I ve checked the php logs, the db log and the local logs on the computer without a trace. Please advise :).

Thanks kr, Jay