So information theory has a point relevant to this. Ever notice some languages seem fast and some seem slow to listen to? The effect is caused by native speakers of different languages speaking at different syllable per minute rates.
Here is where it gets interesting. Different languages encode different amounts of bits of information per syllable of spoken language. When you rate spoken language by bits per minute it seems we all talk at the same rate globally.
The going assumption is that hints at a limitation of the human brain to process spoken language at speed.