The leaves of the mangrove biome disappear, which causes lags

Put the summary of the bug you're having here

What I expected to happen was...:
see the leaves disappear

What actually happened was...:
see the leaves disappear

Steps to Reproduce:
1. Launch any version of Minecraft with the Mangrove biome 
2. Find a Mangrove biome

3. Now some leaves will disappear, causing lags (for smaller PCs)