The same thing is happening to me and my friend. It also happens on xbox. The more items in the inventory the laggier it is. A inventory with like 8 skulkers takes almost 30 seconds to open for me. It was not this bad in the old update.
The exact same thing happen to me also on 2 different words and eventually one world did not break. But ya when I went in it just said building. Then I exited minceaft and when I tried to join I was killed and a second nether portal spawn and all my stuff was everywhere.
The same thing is happening. The more items I have the worse. If I have a few full skulkers it is very bad. However when opening the shukers there was no lag at all. I had a full inventory of full shukers and when trying to-open my inventory it took around 10 seconds, but I could open a placed shukers no problem. It seems to only effect the inventory screen and some others not asbad.