I did some experimentation with FFXIV's video settings and these are the settings that i find worked best for me. I also found that there's really only 2 settings in there that are glitchy and seem to have a major impact on performance.
Here are my settings Which give me 60FPS outside.
Display Mode: Full Screen... It does create some screen tearing. It's quite annoying but playing in windowed mode resolves this.
Window Size: 1680X1050
Multisampling: 16xQ CSAA
General Drawing Quality: 8 (standard) I can set this to 9 no problem but i will drop to 45-50FPS... settings to 10 tho' will result in a 50% FPS drop and bring me to 25-30FPS. The last option is definitely not well optimised and it makes no sense to see such a big impact on performance simply by going from 9 to 10.
Background Drawing Quality: 5 (high)
Shadow Detail: Highest
Ambient Occlusion: Off, Turning it on will result in a 50% drop in FPS just like putting general drawing quality to 10. I don't see any visual difference other then this weird black line across the screen, splitting the screen in two. One side in a permanent shadow and the other side bright. It is quite annoying.... a glitch perhaps?
Depth of Field: On
Disable cutscene effect: off (unchecked)
Enable hardware mouse cursor: on
Texture Quality: High
Texture Filtering: Highest
These are my system specs:
CPU: AMD Phenom II X6 1090T @4.0GHZ
MEMORY: 8GB 1600MHZ 7-8-7-20 NB @ 3000
VIDEO: Sapphire 6990 880Mhz core. Ati drivers 11.5
HDD: 2X (2X500GB in RAID 0)
OS: Windows 7 Ultimate x64
Hope this helps someone.