Enable buffer region extension should be left enabled as it speeds up the process of 3D modeling applications that support the GL_KTX_buffer_region extension. The next option, allow the dual pane extensions to use local video memory deals with the GL_KTX_buffer_region extension again, You will want to leave this option checked.
The next option on the list is to use fast linear-mipmap-linear filtering. This will increase performance slightly at the cost of some image quality. Unless you're using an older video card there really isn't any reason why you would want to have the option checked as the performance increase is negligible. The "disable support for enhanced CPU instruction sets" option should not be checked unless you're having trouble with your drivers and video card. Finally, "force 16bit depth buffer" will increase performance at the cost of some image quality, we recommended that you leave this option unchecked if you have a GeForce2 or higher.
Default Color Depth for Textures
This option allows you to set the color depth for textures in OpenGL games. 16bit offers the greatest level of performance while 32bit will offer the highest image quality.
This option allows you to choose the buffer-flipping mode for full-screen OpenGL games. Auto-select and use block transfer are the two options, leave auto-select enabled to allow the drivers to determine the best mode based on your hardware configuration.
Like in Direct 3D you are presented with three options, on by default, off by default and always off. We recommend that you set it to on by default as that will eliminate any possible image quality issues in games that have a higher frame-rate than the monitor's refresh-rate.
Anisotropic filtering is an advanced form of texture filtering that will sharpen the texture quality of games beyond that of traditional trilinear and bilinear filtering methods. There are four different levels of Anisotropic Filtering in the drivers, off, 2X, 4X, and 8X, the latter of which offers the highest level of image quality. If you have a GeForce3/4 you will definitely want to take advantage of Anisotropic filtering, though the level of which is based on personal preference as the higher the setting, the greater the potential performance impact.
The clock frequencies' tab is activated only when the Coolbits registry hack is applied, and allows manipulation of the clock frequencies of their video card's memory and core. This tweak is widely available online, and a simple search on one of the popular search engines will be all that is needed.