How optimally to make API requests to Bitrix

did someone have experience? Please share. I work with their CRM, try to unload all data about our leads through their API to my base. This will be a daily procedure. But for now, a trash - 50 pcs to make 151 = 1 + 50*3 Requests on a pack of leads. Given the fact that they have a restriction of 1 request of 0.7 seconds, and leads 30,000, hands are lowered. Their documentation (as well as the data structure) to the API leave much to be desired. Who did how? Share experience, please !! I connect via webhuki.