Very high CPU >95% after we migrate to PostgreSQL version 16.1

Question

We recently migrated RDS PostgreSQL from 11.22 to 16.1 but we notice queries are taking more time and most of the time CPU is > 95%. does anybody else faced this issue? any recommendations to improve performance?

We also tried by ending the sessions but we still notice ~60% CPU. in previous version most of the time it was < 10% but after upgrade we continuously see high CPU. Any best practices post upgrade to improve performance?

Instance class : db.t4g.medium

Thanks in Advance

Answer 1

We did the following and now CPU is much better:

1. Reindexing
2. vacuum analyze