> Solution: I upgraded the database instances to 64 GB ARM servers with reserved IOPS and their batch data transformation tools went from taking 16 hours to 20 minutes. Also the DB replicas went from having 4-6 weeks of replication lag (again, completely unmonitored for years) to real-time sub-second updates across regions.

Inverting binary trees really came in handy this time. This is why we need these algorithmic coding tests people. *Sarcasm