Frame rate

FPS (Frames Per Second) is how many frames are displayed per second by a video device. Frames are still pictures that when sequence together form a fluid animation that is the basis for all moving media.

Low FPS will result in a “choppy” gaming experience, as far as looking like a slideshow in extreme cases. Difficult calculations (like blowing up huge loads of TNT in minecraft) can decrease the FPS temporary down to a complete stop for some seconds.

Increasing your FPS

 * Turn down your render distance (default Shortcut Key: F; You can also press ESC and change it under options.)
 * Set in game graphics from Fancy to Fast
 * Do not run other programs while Minecraft is open
 * Turn off Aero in Windows Vista/7
 * Check video card drivers and make sure antialiasing is turned off in the global settings

Third party methods
These mods are not guaranteed to work, can contain malicious files or corrupt your Minecraft program. Be careful when downloading and installing them.
 * Optifog, is a mod which can substantially speed up and stabilize Minecraft's framerate.
 * Optimine, is a mod which optimizes several routines in minecraft and thus speeds up the game. ( Updated Version)
 * There are also guides available on how to manually increase FPS by editing various files in your system.
 * Not exactly a mod, but using a ramdisk greatly improves the performance of minecraft by storing the save files in RAM, which is much faster than a hard drive. However, there is some risk involved, if the computer crashes, you will lose all progress since your last backup to the hard drive.