That's not really getting me to try again either :p
World Tier 3 monster kill XP has been buffed by 5%
World Tier 4 monsters kill XP has been buffed by 15%
Also keep in mind this joins a bunch of other XP-boosting patches in the past. Last week, Blizzard also buffed the XP gain urn in Season of the Malignant to go from an 8% XP buff to a 20% XP buff, making seasonal play by far the fastest way to get your characters to the highest levels in the game.