I was at a customer site recently and introduced to their 'performance managment' team. Asking the nature of their job, I discovered their primary function was to manage desk moves - People Performance. At another company, I found the performance management team was responsible for monitoring the capacity metrics from the IT estate; and at another I found they were measuring the IT applications' response times.
It made me think that throughout the IT industry, there's no consistent understanding of 'what is performance?'. The inter-dependencies of complex systems mean that each of these companies was performing an aspect of performance management, yet none grasping the complete picture.
A system which displays good performance characteristics is responsive, efficient and scalable. Bad performance characteristics result in poor availability and high costs. When was the last time you were impressed with the performance of an application?