If you are running your ASP.NET MVC application on Microsoft Azure (IaaS or PaaS), then do the following at least at before the first deployment.

• Scan your code with static code analyzer for any type of code debt, duplication, complexity and for security.
• Always enable the Application Insight, and monitor the performance, browsers, and analytics frequently to find the real-time issues in the application.
• Implement Azure Redis Cache for static and less frequent change data like Images, assets, common layouts etc.
• Always rely on APM (Application Performance Management) tools provided by Azure.
• See application map frequently to investigate the communication performance between internal parts of the application.
• Monitor Database/VM performance too.
• Use Load Balancer (Horizontal Scale) if required and within the budget.
• If your application has the target audience all over the globe, then use Azure Trafic Manager to automatically handle the incoming request and divert it to the most available application instance.
• Try to automate the performance monitoring by writing the alerts based on low performance.