Why Use the Texture Extension?

Using the texture extension, you can improve your program as follows:

Save space. Use the formats best suited for the texture-memory size of a specific system. Smaller internal formats use less texture memory so more textures can be simultaneously resident in texture memory. This can be especially useful if you want to fit a texture into the 16-bit texture storage on current machines.
Increase speed. The extension offers a fine-grained selection of sizes. At times, you may prefer using 16-bit textures to using 32-bit textures because the increase in rendering speed outweighs the slight decrease in image quality. Smaller textures are usually faster and may therefore be preferable, if sufficient.
Predict texture size. Use the texture extension's proxy mechanism to determine whether a texture you intend to use fits into available texture memory.