what mialo said...just remember it only drops on mobs lvl 20 or lower. You can't really "farm" it, but here's what I do with somewhat limited play-time:
Between DMF's:
I don't usually have enough play-time in a month to get all 7 DMF artificats so I run Wailing Caverns until I get both the
Monstrous Egg and the
Mysterious Grimoire. This also gives me a chance at the
Recipe: Swiftness Potion, the
Deviate Hatchling,
Elixir of Minor Agility, and the
Mechanical Squirrel Box. Once I get both of those artifacts, then I move on to BFD, Stocks, and PvP for the other artifacts. (got the Squirrel so far)
During the DMF for the 250 kills quest:
I'm Horde so I can kill stuff in the Azureload Mine in Hillsbrad Foothills. This gives me a chance at the
Recipe: Swiftness Potion,
Mechanical Squirrel Box,
Elixir of Minor Agility, and the
Cat Carrier (Black Tabby). (found two swiftpot recipes in the cave so far).
So basically ask yourself "what do I want to do that ALSO gives me a chance of getting the swift pot recipe".
Edit: So the main difference between between RFC and WC is that there's no hatchling or DMF artifacts available in RFC. I'm not sure about DPS queue times between the two as I'm a tank so that's all foreign business to me.