In this chapter, we are going to improve the performance and scalability of our REST API. When we make each improvement, we'll use load testing and performance tools to verify that there has been an improvement.

We'll start by focusing on database calls and how we can reduce the number of calls to improve performance. We'll then move on to requesting less data with data paging. We'll also look at the impact that caching data in memory has on performance.

Then, we'll learn how to make our API controllers and data repository asynchronous. We'll eventually understand whether this makes our REST API more performant or perhaps more scalable. 

We'll also learn how the garbage collection process can harm performance and why it's best to let ASP.NET Core handle binding requests to models.

In this chapter, we'll cover the following topics:

• Reducing database round trips
• Paging data
• Making API controllers asynchronous
• Caching data
• Reducing garbage collection