How to check if a large list of users are friends with a small dictionary of target users on Twitter using Twitter API Python

Question

So I have a list of around 6k usernames that I need to go through and check to see if they are following anyone from a target list of about 20 names. I have no idea how to do this efficiently since it seems that the rate limit caps me at 15 users every 15 minutes? I tried going through each of the 6k user's followers and checking if a target name pops up but I get rate limited really quickly, and the same thing happens when I try to use the show_friendship() function. Is there any logistically efficient way to do this? Thanks!