We have an Odoo 11 Enterprise installation hosted over Amazon AWS with load balancer & using RDS on the database, we have noticed that when an ORM is executed for a singular record the resultant query contains where id in [id] which on a bigger scale is consuming more time then ideal and we would like to optimize it. Is such a change possible and if so how can we change it?
The short answer is that there's no simple solution to this at a broad level. If you happen to be analyzing a broad select query that is structured the same way for every data model in the system, it would take rewriting portions of the Odoo ORM which is honestly just very risky.
But also, it depends on what query you are specifically looking at. There's a chance that you could pick and choose certain cumbersome queries and try to optimize those individually. If you have any custom code installed into your instance at all, that would be the place to start to ensure that it's not slowing anything down.
Anything past that, you are going to need a developer to look through the core ORM functionality in https://github.com/odoo/odoo/tree/11.0/odoo and at what point the specific queries you are talking about are getting generated. Then you can see if there's any possible way to extend small sections to make specific queries faster.