The “Render audio using audio card buffer size setting” function should be selected (checked) 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.
