OptiFine 1.8.1_HD_D (Classic: includes built-in support for HD textures, HD fonts and BetterGrass, MCPatcher not needed)
this mod adds a lot of options for better looks and performance. Doubling the FPS is common.
Moves fog away, adds mipmaps, chunk loading control (mod CAF), Smooth FPS, brightness control, VSync and many other.
Download OptiFine 1.8.1_HD_D (fixed white spiders and endermen, added option Fog OFF, SmoothInput is default ON): Download 1, Download 2