I had a world that was less than 10 MBs in size, after downloading beta 1.11.0.5 I played on the world and even though not much was changed its size grew to more than 35 MBs, after this I started getting some lag where if I break blocks I won't hear their breaking sound or see the particles and after more than 15 seconds I'll see all the blocks getting broken together, or all the blocks I broke will come back.

After I close and opened the game the world started to take more than a minute to load, the chunks take a while to load too and the beta text shows that it's using more than 1GB of memory and it keeps increasing as I'm on the world, and once it starts using more than 2GBs of memory the game crashes. Also in the beta text it shows the "ServerTime" which usually keeps changing but just stays frozen in my world and entities don't move at all.

Steps to reproduce:

1. Open the attached world.
2. Without moving, watch the server time and memory usage information in the Beta heading.
3. Proceed to one of the buildings and open doors and chests.
4. Mine some blocks.

Expected results:
Server time and memory show a normal pattern of fluctuations. Doors and chests play their normal open/close sounds. Blocks break instantly.

Actual results:
Server time cycles between periods of normal fluctuation and stalls. While stalled,

• Doors open and close without playing sounds.
• Chests do not open when interacted with.
• Mined blocks do not break.
• Memory usage first rises, then falls back to normal, ending the stall.

Also, some of the LevelDB files in the saved world are much larger than normal, up to tens of MB. Each time you quit and save, they grow larger.

Additional example:
This world was provided by maucvs (Thank you!) as a sample of a 1.11.0.3 world that develops the problem after upgrading it to 1.11.0.5.