As described in “About latency” in the Audio Basics chapter, you generally want the lowest possible latency, to get the best response when you record and play in Reason in real time. However, selecting too low a latency is likely to result in playback problems (clicks, pops, dropouts, etc.). There are several technical reasons for this, the main one being that with smaller buffers (lower latency), the average strain on the CPU will be higher. This also means that the more CPU-intensive your Reason song (i.e. the more devices and audio tracks you use), the higher the minimum latency required for avoiding playback difficulties.

The “Render audio using audio card buffer size setting” function should be selected (ticked) for best plugin performance. When selected, the audio batches are rendered internally according to the set Buffer size (see “Making Buffer Size adjustments in the Reason Preferences dialog” above). For example, if you have a Buffer size of 512 Samples, each audio batch will be 512 samples internally. Raising the Buffer size will let Reason process larger audio batches in one go, which is often more efficient. Many plugins are also more efficient when doing larger audio batches. if you are using DSP-heavy VSTs (mastering effects, for example), these will run a lot smoother with this function selected.