High-Speed Machining uses an 80-block look-ahead function to plan the path, and can process at a speed of up to 1000 blocks per second. That is 1 block every millisecond (1/1000 of a second). This assumes no change in direction or velocity are needed to stay on the programmed path, which is not realistic.
Another function in HSM combines extremely short strokes (less than .0002" or .005 mm) with the previous block or the next block when the change in direction is below a specific limit. This allows the machine to execute smaller strokes – like those often found in dynamic/high-efficiency milling – without a dramatic reduction in velocity, or deviation from the toolpath.
In order to maintain smooth, fluid motion, your program should not contain code that takes less than one millisecond to execute.