World Lag with jumping sun

It occurs only in one World (little one with 43 Mo). Survival mode.

1- Game clock is very slow : mobs moving slow, red stone reaction takes a lot of time ..

2- Sun is moving backward every 20-30 secondes then seem to progress normally until next jump. So it is almost Endless day/nigh.

3- Controlling of my character is ok, and game framerate is very smooth. But action update doesn't work (like eating -> Normal animation but no food bar goes back immediately and food item is back in the inventory.