You need to know what differences there in configuration between my.cnf and RDS DB-Parameter:
All default MySQL settings that would normally be written in a my.cnf. All values are the same in RDS with the exception of two which are mention below:
·         max_connections
·         innodb_buffer_pool_size
Amazon set the following values based on server model:
If your CPU is averaging > 70% or so, you might want to start planning on an upgrade.
Before Upgrading your Box, ensure below check points:
|-> Ensure how much DB connection min required by your application
|-> Ensure NO Slow Query running more than 10sec
|-> Ensure is any scripts making more DB connection with query for select / update / alter etc…
|-> Is there any network latency between DB and application?