I respecd my mage from frostfire to arcane and got a huge dps increase. From 1300dps to 1900dps according to recount at the end of full heroics. I could tell the difference right away in how fast mobs were dieing. These are heroics I always farm and know my dps levels.

spec: 55/3/12
/castsequence Arcane Blast, Arcane Barrage

I will try out some other casts like:
/castsequence Arcane Blast, Arcane Blast, Arcane Blast, Arcane Barrage
and
/cast Arcane Blast