You have already know that the chip has two texture blocks on each of 4 pixel pipelines (like the GeForce2 GTS/Ultra). But the difference lies in a possibility of accumulation of results of their work, and due to this we can combine up to 4 textures at one operation. In case of trilinear or anisotropic filtering there are two block enabled at the same time, thus reducing a number of textures combined simultaneously (e.g. one trilinear and two bilinear textures). In modern games the scene is built at 2-4 operation using two textures each. We should expect a noticeable performance decrease especially when using 32 pixel anisotropic filtering, but in a real application only one texture, as a rule, is filtered with such looses. Lighting and reflecting maps, detailing textures and others do not require even a trilinear filtering. So, when enabling anisotropy filtering you will get a fall in speed (in the worst case two times decrease).