Harvest garden causing massive lags

Normaly i have my fixed 50 FPS in the garden then i walk near some freshly harvested garden fields and i get massive FPS drops between 0 and 50 up and down. Once i walk away from the corner the FPS go back to normal. There is somehting very weird going on in this corner.

Here is video footage: https://www.youtube.com/watch?v=YuTg4eJX3_4