It's not massive, but yes you certainly notice the difference. I have the 42k speed horse my buddy has the common horse both level 50 all points in speed and i leave him behind in Cyrodiil all the time.

Okay that's exactly what I was worried about lol. I'll get myself a light horse then screw it.

This was exactly what I was wondering - how other people ride way faster than me on my level 50 common horse in Cyrodiil. Thanks for the info and to the original poster for asking the question.

Depends on how you use them I guess. Since I like to harvest, I found that the best use I make of my horses are in towns between WayShrines and Banks or Forges, from a Wayshrine to a definite destination when I'm in a hurry or crossing a zone I've fully explored already. And truly I could do without them, most of the times it barely gets me there faster there than sprinting.

I raced with a friend once who had invested all in Speed when I made an even investment on Speed and Stamina. He was a little bit ahead of me at first but then I caught him up fairly easily when he ran out of Stamina and I still had some to spend... No flagrant difference.

In Cyrodiil however, a fast and strong horse is usefull as you sometimes have to run through vast empty spaces before getting anywhere of interest.

As for fleeing from mobs' attacks when they're in pursuit, I never had any trouble with that just sprinting in PvE - in PvP, Im not sure you'll want to waste the 2 secs it takes to mount - half the time my horse disappears when I mount and I have to do it twice before it works properly. May be worth it when you're the one pursuing an enemy, I still have to find proof of this.

Maybe I'm not making the best out of my horses yet, but so far I have not been able to find them very useful, unless perhaps you want to perk it all as a mule for cheaper inventory space (they get saddle bags after a certain amount).

I find the Imperial Horse (I guess that is the same as Common) is fast enough for me with 30 points in Speed (15 you get and 15 more than you buy) in the PVE areas. I don't want to go too fast in those areas as I might miss a crafting mat or something. I may bump one up higher just to see, but I think I will stop feeding it Apples at 30 total and go to Oats. Not sure if I need to sprint all that much with a horse, but I don't do PvP.

What I use the horses most for is increased bag space.