Hello!
What is the warlock fastest leveling spec? At least to 80 that is, got to 62, tried Demo and Destr, fiddled a bit with Affli as well, still can't pick a spec.
Curse of Elements(jinx) on one mob
UA, Corr, BoA on 4-5 mobs.
drainlife spam one target, if you start to get low just instant howl of terror the mobs away, repeat as necessary.
They're all efficient in their own way and there's no single solution that beats all others. The fastest spec for you depends on what spec's play style you're better at, which is probably the play style you enjoy the most so just go with that one.