ASP.NET Core is the new, open source, and cross-platform, web-application framework from Microsoft. It's a stripped down version of ASP.NET that's lightweight and fast. This book will show you how to make your web apps deliver high performance when using it. We'll address many performance improvement techniques from both a general web standpoint and from a C#, ASP.NET Core, and .NET Core perspective. This includes delving into the latest frameworks and demonstrating software design patterns that improve performance. We will highlight common performance pitfalls, which can often occur unnoticed on developer workstations, along with strategies to detect and resolve these issues early. By understanding and addressing challenges upfront, you can avoid nasty surprises when it comes to deployment time. We will introduce performance improvements along with the trade-offs that they entail. We will strike a balance between premature optimization and inefficient code by taking a scientific- and evidence-based approach. We'll remain pragmatic by focusing on the big problems. By reading this book, you'll learn what problems can occur when web applications are deployed at scale and know how to avoid or mitigate these issues. You'll gain experience of how to write high-performance applications without having to learn about issues the hard way. You'll see what's new in ASP.NET Core, why it's been rebuilt from the ground up, and what this means for performance. You will understand how you can now develop on and deploy to Windows, Mac OS X, and Linux using cross-platform tools, such as Visual Studio Code.