as I'm sure most people have discovered by now, leveling in Wrath of the Lich King "feels" like it speeds up dramatically after level 70-72. Right now I can't call it anything but an impression since I haven't looked at any XP numbers or rates to confirm (I will when leveling my second character), but the feeling is definitely there. Originally it seemed like it took 8 hours or so for every level (so 80 hours to level 80!), but after hitting 72 my pace has quickened. There are some possible explanations for this, some may explain why it's faster, and some may explain why it just feels faster:
1) I've built up more rest experience lately due to the Thanksgiving holiday, my fiancee's family visiting, and a few days where I lost my Internet access.
2) I only did roughly one instance run from 70-72, but since then I've run Nexus 3 times (cry), and the first two Nerubian instances (AK and AN) once each. Instances give sizeable more experience than soloing (about 2-3x as much). However I haven't run an instance in a level or so and it still feels fast.
3) Quest completion bonus points increase past the starter zones, perhaps to make people leveling in BT/HF pre-70 take longer to catch up.
4) Gear changes. While I haven't replaced all my gear, I have replaced a few pieces (my TBC gear on the druid was mostly badge/ZA/late-KZ with some T5), which may help. More importantly, all my "balance" gear going into Wrath was former healing items, so most of my upgrades are really sidegrades, like trading regen for crit. I keep some healing-slanted items in my bags for 5-mans but my character is more like a boomkin now than when I started.
5) While most of my new talent points have gone into boosting the resto tree rather than the balance tree (I'm doing balance to boomkin and the rest in resto basically), I have received new spell ranks, which might be increasing my damage output.
3 days ago