If you have been working in the IT industry for a while, you will no doubt be aware that the post deployment period of an application can be a stressful period in the project lifecycle. This is the critical time when your new application is used by a large group of users outside of the sanitized testing environment for the first time. To ensure that you get through this period as effortlessly as possible, I recommend that you invest the time in ensuring that you have the areas mentioned above well and truly covered in advance.
Of these areas, the one (in my experience) that has caused utmost pain in post deployment is performance, performance, and performance. Finding out that a brand new application suddenly starts performing poorly when deployed to its user base is something that I have seen over and over again for the past 20 years in Information Technology. I cannot stress enough the importance of Load Testing as an important step in the deployment and post deployment...