Speed up your world loading by not loading nearby chunks every time.
WARNING: This mod may be unstable and incompatible with some mods.
How.
Vanilla Minecraft loads 21x21 (441) chunks every time you load a world. This mod disables this feature.
It does not work.
The effect may not be noticeable on high-end PCs. This mod is designed primarily for low-end devices. There's a video through.