HTTP protocols

Primer on Web Performance

In any complex system, a large part of the performance optimization process is the untangling of the interactions between the many distinct and separate layers of the system, each with its own set of constraints and limitations. So far, we have examined a number of individual networking components in close detail—different physical delivery methods and transport protocols—and now we can turn our attention to the larger, end-to-end picture of web performance optimization:

• Impact of latency and bandwidth on web performance

• Transport protocol (TCP) constraints imposed on HTTP

• Features and shortcomings of the HTTP protocol itself

• Web application trends and performance requirements

• Browser constraints and optimizations

Optimizing the interaction among all the different layers is not unlike solving a family of equations, each dependent on the others, but nonetheless yielding many possible solutions. There is no one fixed set of recommendations or best practices, and the individual components continue to evolve: browsers are getting faster, user connectivity profiles change, and web applications continue to grow in their scope, ambition, and complexity.

Hence, before we dive into enumerating and analyzing individual performance best practices, it is important to step back and define what the problem really is: what a modern web application is, what tools we have at our disposal, how we measure web-performance, and which parts of the system are helping ...