In the previous sections, we gave a brief overview of the primary components that are included in the new Spring WebFlux. We also looked at the new features that were introduced in the Spring WebFlux module and how they can be used.

However, despite the fact that we now have an understanding of how to use a new API to build a web application, it is still unclear as to why the new WebFlux is better than Web MVC. It would be helpful to understand the principle advantages of WebFlux.

To do this, we have to dig into the theoretical foundations of how to build web servers, understand what the critical characteristics of a fast web server are, and consider what may change the performance of a web server. In the following sections, we are going to analyze the critical characteristics of modern web servers, learn what may cause performance degradation, and think about how to avoid this.