The files that you need to change are at and make sure they are set to "read-only" because it will reset.

\TERA\Client\S1Game\Config

in S1input.ini

bEnableMouseSmoothing=False (better mouse control, not necessarily needed to tweak, this is personal if you have a good mouse and want faster response time)


in S1engine.ini

[SystemSettings]
DropParticleDistortion=False
UseVsync=False
AllowD3D10=False
SkeletalMeshLODBias=-1
ParticleLODBias=-1
DetailMode=3
ShadowFilterQualityBias=1
bAllowLightShafts=True (you must add this line yourself there)
MaxAnisotropy=16
MaxMultisamples=4
bEnableVSMShadows=True
FXAA=False
bEnableBranchingPCFShadows=True
MinShadowResolution=1024
MaxShadowResolution=4096 (be careful altering these values on min and max shadow resolution!! check what your card can handle!)

[Engine.GameEngine]
bSmoothFrameRate=True
MinSmoothedFrameRate=25
MaxSmoothedFrameRate=120 (be careful altering these values on min and max framerate!! check what your card can handle!)