What is the best way to look up follower ids for large numbers (>10k) of users?


I am interested in building out the social graph for groups of users. In order to do so, I would like to keep up to date on the followers for each of these users.

Currently, in my small group trial, there are about 13k users for whom I’d like to have this information, but using the follower_ids method, given the 1req / min rate limit, this looks like it would take about 216 hours to complete (longer given that popular users will require cursors), making it impossible to stay current.

Is there any way to get this data in bulk i.e. (request multiple users in a single call, and get the data broken out by user)?
Is there any way to get this data through a call that has no rate limit or that has a higher rate limit?
Are there any 3rd party services that might make this easier?