What is required to run CiviCRM on Amazon RDS?
We haven't tried running CiviCRM on RDS yet but we have been shifting a Drupal installation across to AWS. A few things we've noted so far that are relevant:


It helps if the RDS instance is in the same AZ as the web service
The various RDS instances have differing network throughput. It's poorly documented and can catch you out
Default settings for MySQL/MariaDB RDS from memory don't have caching enabled. You should be mindful of checking the paramater group for every RDS instance
Read replicas can be your friend!