Originally Posted by
Akraen
Your gear doesn't really support frost. It's not that you can't play frost, but you'd want to hit at least 5859 haste (since you're a Goblin) for it to begin to take off. As you say, you cast slow. You don't really have enough haste to enjoy arcane or frost. If I was handed your toon and required to play arcane I'd use frost armor to make life worth living.
You may get a bit frustrated trying to play arcane or frost while gearing up for fire since it requires completely different stats. In this case, you might find it easier just to play whichever your gear supports best, not which is best.
Since you don't have 4pc T15 you'll probably see bigger and more consistent numbers with frost. The playstyle of frost is also closer to fire than arcane is which may help serve as a bit of a primer.
All that said, play what you enjoy. Mage DPS is better balanced than people seem to think.