I am having the low frame rate on my MacBook Pro Retina also.
I hover between 26FPS and 40FPS
Model Name: MacBook Pro
Model Identifier: MacBookPro10,1
Processor Name: Intel Core i7
Processor Speed: 2.3 GHz
Memory: 8 GB
SMC Version (system): 2.3f32
Graphics NVIDIA GeForce GT 650M 1024 MB
Software OS X 10.8.2 (12C60)
I have done the following in exactly the order specified.
I have no add ons installed and have had none since MOP was released.
I have no special hardware connected.
I am running off 5ghz WiFi.
1. Reset UI
2. Reset SMC
3. Playtest with no addons installed.
Maybe the MacBook Pro Retina is just too "different" for WoW?