This is a small, but useful performance increasing mod called OptiLeaves. It changes leaves so they are rendered in a faster, much more efficient way. Depending on your system, it can might be able to significantly boost your framerate!
Here is a comparison between Vanilla Fancy leaves and OptiLeaves:
- Download and install installer
- Download OptiLeaves Mod
- Put zip file into your /.minecraft/mods folder. Do not unzip it. If you don’t have a mods folder, create one.