-PvP- Completely broken for some classes and I mean broken going from both sides of the spectrum, from classes destroying everyone, to classes that can't even kill another player. It's fairly common for a weak class to lose to a powerful class even if the weak class outgears them by 50+ ilvls. That's how broken PvP is and Blizzard doesn't seem to know what to do to fix it other than do blanket damage nerfs/buffs as those are the only changes we've seen.
Get exalted reputation with every faction you can. This relates to the previous two pretty directly. Gaining reputation with most of the factions of Kul Tiras and Zandalar will allow them to sell you high-level gear, while gaining reputation with the Champions of Azeroth faction will grant you levels for your Heart of Azeroth, the neck piece where all of your AP is stored.
Also get the Heirloom Mount. Being able to have basic riding speed from the beginning will save you a lot of time if you're starting from level 1. Allied races start at 20, so this is a non-issue for them. It's important to note that Pandaren can not use this mount until they finish their starting zone and pick a faction. Being Horde or Alliance is a requirement of the mount.
For reference, my previous best time abusing Method-0 in 7.3.5 was 32.4 hours(as show in the old thread). A difference of just over 8 hours; which isn't all that bad, all things considered. And I believe I made several errors along the way, which could be cleaned up in future runs. I believe that that gap could be significantly closed by using a monk's bonus, but I hate playing monk...so...yeah. YMMV