If you skipped Alacrity on your gear, and Polarity Shift isn't cutting it for you, you just might need the on-use Alacrity relic.
That being said, if you didn't totally skip on your Alacrity (you do have at least 8%, right?), then Power, Power, and more Power for on-use.
Then again, I use the PvP relics, because they are better to start with than any of the PvE ones.
I'm at BiS ratio with alacrity/surge.
Seems like everyone thinks power's the way to go, even in a cast time spec. Good enough for me, thanks all.