To your original question, rendering will be multi-threaded by default.
Or are you asking how to run the render on a background thread? If so, that exact question was asked and solved here: How to render an Edit to a new file audio file?
To your original question, rendering will be multi-threaded by default.
Or are you asking how to run the render on a background thread? If so, that exact question was asked and solved here: How to render an Edit to a new file audio file?