Diablo 4 can be a little opaque. Players roaming the wastes of Sanctuary often find themselves asking questions like "Why is that guy so big?" "Where can I get some pants?" and "What do the rats know?" But the question most people ask themselves, almost to the point of obsession, is "How do I level faster?" Well console yourself, traveller, because an absolute legend has figured it out using nothing but the scientific method and a superhuman level of dedication.
The hero in question is a player named Drybear, who has "hand-tested every single permanent Dungeon and Stronghold in the game and compared them together for clear speed, mob density, and how valuable your time is per second spent in that encounter," with the aim of creating a "resource that the Diablo IV community could use to determine the best source of Experience at any given level." The fruit of his labours is—what else?—a spreadsheet of great and terrible power.
Drybear went out of his way to make sure his findings were as accurate as possible. In order to account for differences in monster level—the fact that running a dungeon at a low player level would spit out different XP than running it again at a higher level—he went through the laborious work of "hand counting every mob in the dungeon," before "comparing the mob density across all of them". It's a lot of work and, while I imagine there are probably some faults with the data, the lengths Drybear went to are both impressive and slightly frightening.
You can find the full results over at Drybear's publicly-available Google Sheets page, where each one of the game's 130 dungeons is broken down according to the speed you can clear it in, how much XP it spits out for solo and group players, its "farm lanes" (which I admit is too deep a level of Diablo 4 strategizing for me to parse), and various other bits and bobs of information. It's comprehensive, in essence, and should allow anyone dedicated to efficiency in all aspects of the game to put together a clever, custom-made plan to maximise their returns at all times.
For the rest of us? Drybear put together a one-sheet summary that will just tell you where to go based on whether you're playing solo or partied-up. It even has an optimal route you can follow. There's also a video version, because science has to be a multimedia affair these days to catch public attention.
There is an elephant in the room here, of course. Blizzard is all set to kick off Diablo 4 season 1 on Thursday this week, a big shift that could well invalidate a lot of Drybear's findings. If that happens, then it'll probably be a matter of time before he—or someone like him—is out there doing it all over again to keep the spreadsheet up to date. God bless you, Diablo 4 community, you are all kind of terrifying.