Because CTL is an interpreted language, the performance may be slow. Composite gives you the option of accelerating a CTL program by converting it to a 3d-lut.This will be faster but may contain errors relative to the original CTL program.
To enable acceleration, click the 3D LUT Enable switch in the CTL tool's Processing tab. The Pre-conditioning option allows you to adjust the distribution of grid points in the 3d-lut. If the input image is in scene-linear color space, setting the Pre-conditioning to Log will arrange the grid points in a roughly logarithmic manner which will help distribute the approximation errors in a more perceptually uniform way.
