Yes, this connector is slow. This is due to the way the Twilio API works - with all the Text-To-Speech and Speech-to-Text involved, it always takes several seconds for a conversation turn to complete. There are IVR systems out there that will then just hang up. We know about this problem, but right now there is no other way than configuring the IVR system under test to accept longer waiting times.
By default, a Botium test has to complete within one minute, I suppose that this is what you are experiencing. Using the –timeout switch to extend it to 2-3 minutes would help in this case.