When snow accumulates in areas, especially with tons of grass, the tile entities creates a huge amount of lag. You can see the amount of memory blockentities takes up in the bottom right hand corner. (This example has 2500 grass/snow tile entities in a 50x50 area)

And here's what it looks like without the tile entities in view

• Forge Version: 36.0.58
• Mod Version: 2.3.2

First thank you for your time to test these. I did these too and I know it's laggy too. However optimizing this requires many efforts and I am not good at rendering stuff. So the best choice currently is turn off this feature.