Hey,
I've had fps lag whenever we got Shackles or Lasers last week. So since it's raid tonight my brain wondered if that is caused by the specific Weak Aura by Pottm or by the WA-Addon itself?
The addon it self probably not. There is a know performance bug with image files from addons, if the aura uses any image not from the game files, there is a change to be the culprit.
Also, post the string for the aura.