In most corporate projects that I worked with, the day it went to production started the clock to disband the core team and optimizations were not on the table. When the product works, they move on. The only area where performance optimization is a mandatory step is video games, but that is where your clients are external. Most business software is in the "finally, but barely works" state and new features beat performance improvements.

This is caused by short sighted management that need to deliver and move on. "Long term" is a contradiction with their business model. In this case "long term" means "after product launch".