When you think about C#, you'll usually think about a high-level language, one that is utilized to build websites, APIs, and desktop applications. However, from its inception, C# had the foundation to be used as a system language, with facilities that allow you direct memory access and fine-grained control over memory and execution.

The API was already fast, but on .NET 6, it is much faster! We also saw a reduction in memory consumption:

The Latest New Features of .NET 7 Confirm the Rumors: The FASTEST .NET Ever?

Should I avoid LINQ for performance reasons? 

⚡ Decompilation Tools and High Productivity Utilities ⚡  

Performance benefits of sealed class in .NET 

A Hard Drive Retrospective – SQL Server Edition 

Optimize rendering speed to minimize rendering workload and improve UI responsiveness, which can yield a ten-fold or higher improvement in UI rendering speed. 

Measuring Performance After Migration from .NET5 to .NET 6