How optimally to make API requests to Bitrix

Did anyone have experience? Please share. I work with their CRM, trying to unload all data about our leads through their API to my database. This will be a daily procedure. But for now, it's a mess - 50 pieces to make 151 = 1 + 50*3 requests on a pack of leads. Given the fact that they have a limit of 1 request per 0.7 seconds, and 30,000 leads, my hands drop. Their documentation (as well as the data structure) for the API leaves much to be desired. Who did it how? Share experience, please!! I connect via webhooks.