This mod removes the sounds of animal footsteps, which will reduce stuttering on certain systems; those with onboard sound, primarily. If you have a new sound card (i.e. X-Fi) don't bother, unless you don't like the sounds.
Some people experience horrible stuttering when they ride a horse or fight certain enemies. Characters in the game have distinct sound effects that play when each foot hits the ground, which for whatever reason is too much for some older sound cards (and newer onboard sound systems) to handle. Enemies with more feet (e.g. wolves) make grown men weep. One solution is to open Oblivion.ini and set iMaxImpactSoundCount to a lower value, but "impact sounds" also includes blocks, hits, etc.
Quiet Feet solves this problem by simply removing footfall sound effects from all non-human creatures. Apparently the game uses a different system for humans, so they don't cause the stuttering