The idea of this patch is to bring more realism to the cavalry. Currently light cavalry is slower than heavy cavalry, which makes no sense. The reason heavy cavalry is faster is purely gameplay, but that is also a problem.
Spear cavalry can handle light cavalry but cannot reach sword cavalry.
The patch approximates the movement speed for cavalry, 18.0 for jave / archer and 19.6 for spear / sword / axman. The difference is low and makes it possible for heavy cavalry to chase the lighter.
The other ways to make the units balanced without having to go against realism. Soon balancing patches for the units should appear, which should improve even more.
D2966 is a complement to this patch.