Questing bottlenecks plague the release of every World of Warcraft expansion -- if you were an Alliance player trying to play the night of Mists of Pandaria's release, you probably have nightmares about a certain gyrocopter. This time around, the developers are specifically seeking feedback about such bottlenecks. In the words of QA representative Zorbrix:
Zorbrix has created individual threads for each Warlords zone for beta testers to submit specific feedback. Beta testers, be diligent in reporting potential bottlenecks -- for those of us interested in doing meaningful testing, catching bottlenecks before they go live will undoubtedly have the largest positive impact on gameplay during the expansion's launch.