Architecture–where performance changes come from

One of the most consistent reasons for dramatic performance changes is changes in infrastructure. You can dive into the code and find bugs or do deep research on tuning, but more often than not, putting a cache in the right place or removing a dependency will change performance with orders of magnitude. A quick example would be taking a simple web application and adding a Content Distribution Network (CDN) in front of it. This allows for a global cache of content, reducing the load on your actual applications, assuming the content can actually be cached.

Figure 6: An architecture of a simple web app, before (left) and after adding a CDN (right)

Now, because of this significant change in performance, architecture decisions can also have a dramatic effect on capacity planning. It is highly recommended that you try and get involved in the planning stages for architecture changes. The reasons for this are twofold:

1. You have deep knowledge...