Other than simply changing the options in NWN, itself, I think there are a few threads in the Custom Content forum where people have asked about graphical enhancements. Other than overrides or NWShader, you're mostly going to be at the mercy of whatever custom content haks the module builder used.
There's also the matter of making sure things are running smoothly on your end. You might need to tweak some of your *.ini settings in order to improve performance and I've found, along with searching here, nwn.wikia.com or Google, that the Omnibus can be useful. For instance, to learn more about settings such as "Max Memory Usage" nwnplayer.ini.