What does accelleration do?

[laenzlinger]

In the wiki acceleration is described as follows:

Disabled by default for all encoders. If enabled, acceleration is used if encoding mode is set to Control Change (both 7 and 14-bit variants), Pitch Bend or 7/14-bit NRPN. Acceleration can be set to the following values:

Disabled
Slow
Medium
Fast

But what does it really do? How does it change the behavior of the encoders?