This section will explain the movement speed cap in diablo 3.
I have people asking me to put movement speed affixes in to modded items but the cap will always be 25% from items and paragon. You can stack 300% movement speed on items but the cap will always bring it back down to 25%.The only way to raise beyond this cap is the use of shrines, abilities, and spells. I've seen some modded items out there that's stacking movement speed but little does that modder know that the speed increase on his items does nothing beyond 25%.
Here is the proper way to stack movement speed through the use of spells from legendary items and abilities.
25% Paragon
60% Rechel's Ring
20% Horrify - Stalker
30% Fierce Loyalty
25% Krelm's Buff Belt
25% Wreath of Lightning
25% Boon of the Hoarder
50% Spirit Walk
25% BBV
Having all of the above at the same time will go beyond the 25% cap.