[eluser]nirbhab[/eluser]
As you all know CI is a framework.
It provides a very easy and simple way to arrange our files in MVC pattern.
It would totally depends upon you how you create or extend it.
Server Support is must: how fast is your Live Server and handling multiple thread requests.
How fast is your DB server, and even the Shared Hosting also matters to the Performance of your Application.
While in regarding CI, It would always help you to enhance your Application.
buddy you can surely continue using CI for your HIS.