msSQL Spatial Expert to Optimized Queries and Data stored

I have census blocks that we run a query.. Currently we have 8 million lines in our census blocks table, and comparing it to 5200 lines in another table. Currently with the 2010 census we run less than 10 minutes, but in 2020 data we are getting run times over 16+ hours. We are looking for someone that can do some hourly work, to improve our indexes, and show us why and how to improve our run times with our 2020 data.