If you want to spend as little time on your alt as possible - just do Legion Invasions. You can use sites like (https://wow.gameinfo.io/invasions) to track when the next invasion will be. Log in, fly to the closest world quest, and once there - right-click on the quest's name in your quest log and "Find Group". Sign up for some group, or if there's none - just start your own immediately, and people will come to you. It is 10 times faster to do invasion quests in a group. Once that particular quest is complete - leave the group, and fly to the next one, where you should find another group. Don't expect the group from one world quest to follow you to the next. Then you simply log out until next invasion. You can do 1-2 invasions a day, and each invasion will give you about a level or 1.5 of experience, if you have full heirloom gear. Each invasion will take about 20 minutes.
Currently, it is believed that the War Mode rewards will change depending on which faction is more heavily prevalent with War Mode activated. The Horde have typically had more participating in War Mode, so the reward has been increased for the Alliance to incentivize more participation in War Mode. These rewards could potentially be increased to both the Horde and Alliance to incentivize both factions to higher amounts of War Mode participation.
Dugi’s leveling guide is the leveling addon I’ve always used to level as fast as possible. It will show you where to go and what to do in-game, speeding up the leveling process. This is optional though, as the game already does a pretty good job at showing you where to go at all times. The addon does, however, come with a couple of other nice features and perks.
Kul Tiran human (8.1.5) - "Kul Tiras was founded by fearless explorers who sailed uncharted waters in search of adventure. As a key member of the Alliance of Lordaeron, the Kul Tiran navy dominated the seas of Azeroth with its legendary fleet. But after years of turmoil and hardship, the kingdom grew isolated and vulnerable to dark influences. Thanks to the help of brave heroes, House Proudmoore has been restored and Kul Tiras is poised to fight alongside the valiant Alliance once more."
So much new stuff. The war questline expands. Island expeditions get a couple of new locations to explore. Azerite armor gets tweaked so it’s slightly less stupid than it already is. While we wait for the servers to go back up, Blizzard’s prepared a handy survival guide for Tides of Vengeance. I suggest looking it over, or else risk not surviving at all.
I also noticed that the slowdowns were heating up my graphics card (a GTX1080 with good cooling and a well-configured fan curve). On high but not max settings, I would always hover around 60-65 degrees C, and thought this was normal. After turning auto zoom off, I noticed that my card never gets past 49 degrees C. I'm pretty shocked, as it's a very hot day where I am and I didn't know one feature could affect temps so much. I didn't know my temps could even get that low! Even on full max settings (with 200% resolution scaling etc.), it now can't go over 66 degrees, whereas it used to go up to 74 degrees at times when auto zoom was on.
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