There's a npc in cyrodiil at northern high rock gate, near the bank. His name is Onri Tustin and he says, "Light armor gives you stealth and speed, both vital on the battlefield!"
But I looked it up and from what I read, this is not true and there are no inherent bonuses to stealth or speed with light armor. Medium armor has passive skill for stealth and speed, but I'm pretty sure without passives, there are no penalties/bonuses to speed or stealth when it comes to armor types.
Is this just a lore/immersion thing or is there any truth to what he says?