Fastcraft

Fastcraft is a sophisticated mod created by Player, which is intended to improve the client and server performance significantly without any gameplay changes. It is intended to be useful for anything, even fast PCs and servers can benefit. However, like all mods intended to improve performance (such as Optifine and FPS Plus+), it does have the possibility of decreasing performance. For this reason, as well as legal reasons involving the license of Fastcraft, it is not enabled by default in any FTB modpacks.

Optimizations/tweaks Fastcraft applies are very broad and can include the following:
 * FPS improvements (client), benefits depend heavily on PC, mods and the world
 * TPS / simulation improvements through faster code and better algorithms
 * Lag spike elimination from world generation, light calculations and chunk loads
 * RAM savings of around 200 MB for a decent amount of mods
 * Faster chunk loading (client/server) and rendering (client)
 * Faster game startup
 * Minor network bandwidth reduction in some scenarios