CustomerCentrix

There can be unique performance issues introduced when running your application across multiple company networks or in different vendor clouds. Some architects decide to address dispersed user populations by putting a copy of the app in their geography. For instance, LoadStorm runs in Virginia, California, Singapore, and Ireland in order to provide testing that has user traffic originating on different continents.

Any complex data center or network environment can blow up your performance testing models if you don't account for them in test planning and execution. You can get the proper steps built into your scenarios such that the relative volume of user types (anonymous, buyers, admins, etc.) are represented. That said, you probably want to test the scenario volume coming from a corresponding geo.

Application lifecycle performance testing and monitoring strategies on SearchSoftwareQuality by Mike Kelly is an interesting read that has some good info about load and performance testing.

Selected quotes:

"Application performance is often a series of tradeoffs that occur throughout the application lifecycle."

"If we allow for emergent design, we may not recognize the need for a focus on low-level performance metrics early in the project"

"This is why application performance testing and monitoring can be so important for some projects. As teams work to test pre-production, and monitor post-production, they are often looking to tune their application to an ever-changing operating environment with an evolving user population. Tuning application performance isn't unlike sound-mixing – where you're asking people with some specialized skills to "listen" to your application and move a bunch of knobs, sliders, and dials to obtain optimal performance."