How video card helps to render fast?

The FX features DDR, DDR2 or GDDR-3 memory, a 130 nm fabrication process, and Shader Model 2.0/2.0A compliant vertex and pixel shaders. The FX series is fully compliant and compatible with DirectX 9.0b. The GeForce FX also included an improved VPE (Video Processing Engine), which was first deployed in the GeForce4 MX. Its main upgrade was per pixel video-deinterlacing — a feature first offered in ATI's Radeon, but seeing little use until the maturation of Microsoft's DirectX-VA and VMR (video mixing renderer) APIs. Among other features was an improved anisotropic filtering algorithm which was not angle-dependent (unlike its competitor, the Radeon 9700/9800 series) and offered better quality, but affected performance somewhat. Though NVIDIA reduced the filtering quality in the drivers for a while, the company eventually got the quality up again, and this feature remains one of the highest points of the GeForce FX family to date (However, this method of anisotropic filtering was dropped by NVIDIA with the GeForce 6 series for performance reasons).