I just ran two speed runs of the Death Knight starting experience - one on the live servers and one on the PTR - and took down some numbers. I used no 'looms, did every quest, and only killed as many mobs as was absolutely necessary to get the job done.
This issue we're seeing on the PTR appears to be caused by a disconnect between the amount of XP given for quests and the amount of XP it takes to reach levels 55-58:
During both runs, basic quests at all levels were rewarding 13,100 XP, special quests were ~17.5k XP, breadcrumbs were 875 XP
- 154k XP was required to hit level 56 - got there just before accepting the "Massacre at Light's Point" quest
- 158k XP was required to hit level 57 - got there when rescuing Koltira ("Bloody Breakout")
- 163k XP was required to Hit level 58 - got there when turning in "The Battle for Ebon Hold" (you can't get much more perfect than that...)
That's ~475k total XP required.
--- (I was at 55 and 85% before accepting the "Massacre at Light's Point" quest)
- 216k XP was required to Hit level 56 - got there when completing "Victory at Death's Breach"
--- (I was at 56 and 47% when rescuing Koltira ("Bloody Breakout"))
- 222k XP was required to hit level 57 - got there after completing "An End To All Things..."
--- (I was at 57 and 24% when turning in "The Battle for Ebon Hold")
- Level 58 would have required 228k XP - never got there.
That's ~666k (appropriate amount for Unholy DKs) total XP required.
That's an approximate 40% increase in XP required, so if the DK starting experience quests rewarded ~40% more XP, we should be 58 when heading out into the really real world again.
What I didn't say in that forum thread (because it was kind of off-topic) was that I really appreciated the change in combat pacing. It took me 65 minutes to complete the run on Live, but took me 80 minutes on the PTR. That 15 minutes was pretty close to 100% combat time.
Combat rotation to kill a single, normal mob at my same level (keep in mind, I used no 'looms):
- On Live: Outbreak -> Festering Strike -> dead.
- On PTR: Outbreak -> Festering Strike -> Scourge Strike x2 -> Death Strike -> dead.
That's right! No one-shotting! Not even three-shotting! I actually died on the PTR - during the starting experience! - by pulling too many mobs as a non-tank. And I'm a well-seasoned DK main!
Anyways, I have more testing I want to do: I transferred 2 level 80 characters, a warrior who's going to go through Cata and a warlock who is going to go through MoP. We'll see how they feel leveling to 85/90. Of course, a proper test would be two characters of the same class but... I have to enjoy this to stick with it and I need variety! :P
If anyone wants to join me on the PTR, let me know here and we'll hook it up! I'm on the US PvE server, Horde side. (I'm running Horde so that the leveling experience won't get ruined for me before it makes it to the Live servers.)