Clock speed without audio module

Why is a set bpm double as fast when used in a patch without an audio module?
At 120 bpm I get 4 triggers per second, with an installed Apple Audio module 2 triggers.

The audio module is used intenally to set the timing in Rack, thus you should ideally always have one set up to a valid audio device.

Without a blocking module like Core Audio, the engine loop runs freely with no blocking. When the engine realizes that 2s of timesteps have been processed in 1s (or something, don’t remember the numbers exactly), an emergency sleep() is called for 1s.

Thank you, Marc & Andrew, for your explanations.
I am relaxed now knowing that it is a “normal” behaviour.