Some people have still been having issues with the UI lag. While the settings from http://tera-online-guides.blogspot.com/2012/10/tweaking-tera-onlines-game-performance.html has helped improve game performance and fixed errors others still notice a problem with some video cards. A friend of mine from K-Tera has been kind enough to share some other settings that might help to address this problem for others so I'll post what she shared.
These settings are found under your Nvidia Control Pannel:
Antialiasing - FXAA On
Antialiasing - Gamma correction On
Antialiasing - Mode Enhance the application setting
Antialiasing - Setting 16xQ CSAA
Antialiasing - Transparency 8x (supersample)
CUDA - GPUs All
Maximum pre-rendered frames 3
Multi-display/mixed-GPU acceleration single display performance mode
SLI rendering mode NVIDIA recommended
Texture Filtering - Anisotropic sampling option on
Texture Filtering - Negitive LOD bias Allow
She also recomends using the core unparking which was explained in the first guide I published as well. But keep in mind if your on a laptop core unparking will not be an option for you because it causes the system to use more power and laptops are made to be power efficiant since they run on a battery. Core unparking does not work for systems which are only single cores as well it only effects multi-core processors because all your doing is taking off the windows limits that makes the system use all 4 cores instead of locking them and making them inactive during when they are not being used.
Another thing she also recomended was downloading and installing beta legacy drivers from: http://www.geforce.com/drivers/beta-legacy
Reasoning for this is because she says many of the beta drivers for the newer cards boost performance over the main current drivers and will improve your game performance even more. She said if tweaking your system this way doesn't improve fps performance you could look to your ram and make sure that your not over your usage as well as check for any virus's on your system that could be causing fps drops but other then what was posted on the above guide there's not much you can really do to improve fps.