Abstract: When procedural models based on implicit functions are used for defining complex shapes, the final model may become slow for rendering. We propose an algorithm for accelerating such rendering for free-form shape modeling where some initial shape is gradually modified by other implicitly-defined shapes with relatively smaller sizes compared to the final shape. The algorithm then adds additional functions to the final function script, which makes the rendering of the whole shape faster. The resulting accelerated function scripts can be then rendered on any suitable rendering platform that we illustrate by using function-based extension of VRML/X3D and POV-Ray.