the spec of my mage is both arcane and frost yes it happen*(ed)* on both.
I was getting so frustrated that I was doing a lot of research and came across FPS issues in the old forums. This post right here sounded so familiar to my situation.
I had castsequence macros in my character personal list:
#showtooltip
/cleartarget [dead]
/targetenemy [noharm]
/castsequence reset=target Slow, Arcane Blast, Arcane Blast, Arcane Blast. Arcane Blast, Arcane Barrage, Arcane Missiles
plus one for frost
Removed these macros and I am doing ok hitting at the most 41mb usage in previous tested areas