General mllite_test.c questions, data transfer rate

Hello there, I have a couple questions about the mllite_test.c file and how it works.

What is the frequency of the main loop?
Does the main loop wait for any interrupts (timers, gpio, etc)?

I'm looking to add some custom code but I'm wondering how much time I have between frames, and where might be the best place to insert my code.

Thank you,
Paul