With 8.0, Blizzard introduced World of Warcraft’s second ever stat squish — where all the numbers in the game are lowered across the board for clarity. While it may make the game easier to read, it has caused some serious in-game problems. Since the patch, Blizzard has been throwing out hotfixes each day, fixing things that the stat squish either forgot to alter or simply broke.
Fully rested experience (this is the blue color your experience bar takes instead of purple) grants 200% more experience per kill. Quest experience does not work the same as mob experience. Instead of just using the rested bonus, quest experience pushes the bar further upwards extending the rested bonus. Say if half your experience bar is blue. If you turn in 10 quests all at one the normal experience from them all could boost a character a full level. Unlike mobs where the experience gain will use up said bonus - the quests merely 'push' the bar further. Doing this could net you a level and still have the 200% bonus for mob kills applying to milk the rest bonus.
One of the most profitable ways to farm in patch 5.4 is to buy Potions of Luck from the auction house and head to the Vale of Eternal Blossoms. In the northwestern corner, specifically the Ruins of Guo-Lai and the Guo-Lai Hills, there's tons of mobs that can be aggroed in huge groups and AOE'd down. The Potion of Luck will increase your chances of finding loot on the monsters, and these mobs in particular drop good crafting mats, Skycrystals, motes of harmony, and Gou-Lai keys. Many guides tout this as the greatest way to farm gold; depending on your ilvl and clear time, you can earn anywhere from 2.5-7.5k an hour.