Is occlusion culling enabled? Were you facing the people? What did the loads look like on your cpu and gpu? Is there HDD activity during this player loading phase? Textures might not be cached in the GPU's RAM at the time. It ran fine in beta phases because there was a fraction of the people playing compared to now. It is not a driver issue, it is a programming issue. It is FFXIV's use of DirectX 9 as a rendering pipeline. Some people say they do not have issues, what they are saying is their FPS loss is not as great as yours. Whether they've customized FFXIV's graphical settings or not, EVERYONE experiences a drop in FPS when entering an area with a large number of players. Even PS3 players do.
I dare someone to post a video of their system settings window visible while they transition from an area with few players to a crowded area. I guarantee their framerates drop. Even AMD's 13.8 beta drivers, which explicitly mention improved support for FFXIV have not prevented this drastic framerate loss for some people.
This is caused by DirectX 9. It's an issue between DX9 and your CPU and the only thing you can do about it is lower the fidelity of shadows and pray the transition to the DX11 rendering API alleviates the issues. Read the links I've posted and stop stating it isn't the problem because phase 3 beta and the benchmark were fine. Both instances are COMPLETELY IRRELEVANT to the current state of the game. There isn't 60 -100 people in various sets of armor running around on your screen at the same time in either scenario.
Here's some more information regarding DX11 and it's multiple features directly integrated into the API. Realize that SE has basically tried to take features inherent in DX11 and push them through a DX9 graphical API, which is very inefficient and can impact performance on all systems across the board:
http://www.maximumpc.com/article/fea..._deconstructed
http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx
Nvidia has supported DX11 multithreaded rendering since their 270 series drivers. AMD will apparently not support it. There are very few games that support multithreaded rendering in the first place, but they also don't have the same rendering obstacles that MMOs have to deal with, so they run just fine on a single thread. If FFXIV was never written with this type of rendering in mind then performance gains from the DX11 API will be minimal. The only improvement seen will be a smaller impact in performance when shadow, lighting, and tessellated geometry are set to higher qualities.