Earlier this year we talked about the current leveling problem in World of Warcraft and Blizzard's vague promise to fix it. Go ahead and give the article a read so you're up to speed. You didn't, did you?
To sum things up the powers that be "squished" stats to prevent them from getting too out of hand, but as a result, leveling new characters (particularly levels 60-80, which were problem areas) was slowed. While vanilla (original) WoW fans were fine with the change as it was still a swifter leveling process than in the past, it understandably upset a lot of new players who weren't used to the grind: not to mention veterans who were looking to quickly level alts to get to endgame. It was an unfortunate situation for everyone involved. Nearly three months after addressing the issue Blizzard has seemingly found a fix.
According to the WoW database Wowhead, Blizzard has judiciously reduced the amount of experience required to level-up for characters at the 20-120 stage in the PTR (public test realm, or basically beta testing for new patches). It starts to really bump up from levels 23 to 24, which requires 10% less experience overall (a significant amount), but once it ramps up to level 60 it really gets going with a 40% reduction nearly through level 70, where it steadily goes down to roughly a 30% reduction. It differs from level to level but it's a great start.
What does this all mean? If you think leveling is sluggish you should wait until patch 8.1 (slated for December 11) arrives when the experience requirements drop. For now, go grab those Allied Races so they're prepped for the changes. You can find the full data set below.
8.1 PTR Build 28366 [Wowhead]