You can't base decisions on assumptions. What you can't measure you can't manage. Familiar? Of course, and what you want to do with your software is specifically what's hinted: measure how people use it. Azure Application Insights is a tool for this, being an application telemetry service. Now we created an Orchard module for it for easy integration!
When building a web-based service that will be used by people all around the world you also have to think about network latencies that are imposed by geographical distances. Your service itself may be very fast, but it won't matter if users on the other side of the globe will experience it with a delay of 1 second.