Microsoft .NET Code Analysis for Performance

If you’re not using .NET code analysis tools to catch performance issues, you’re basically flying blind—and hoping your code magically runs fast. Spoiler: it won’t.

Modern .NET gives you powerful analyzers (built on Roslyn) that scan your code and flag performance problems before your app ever runs. These rules cover everything from inefficient allocations and string handling to collection usage and API misuse—surfacing issues as warnings or suggestions right in your IDE or build pipeline.

This page takes those recommendations to the next level. It doesn’t just list rules—it breaks them down with real examples and benchmark data, showing you exactly how Microsoft’s performance guidance plays out in the real world. It also shows you how to dial in your .editorconfig so these rules actually work for you—not against you.

Because here’s the truth: most performance problems aren’t caused by “big mistakes.” They come from small, repeated inefficiencies that add up over time—and that’s exactly what code analysis is designed to catch.

Bottom line: if you want to write high-performance .NET code, you don’t just guess—you analyze, measure, and optimize. Turn on the analyzers, tune the rules, and let your code hit like a perfectly tuned riff instead of a noisy mess.

Code It Any Way You Want: Performance Impact of Sealing Attributes

Structure Performance: Implementing Operators

Collection Performance: Exploring the Performance Impacts of Array Properties

String Performance: The Fastest Way to Get a String’s Length

Reference Type & Structure Performance: Disposable Types

Collection Performance: Finding First or Last and Count

Microsoft .NET Code Analysis: Boosting  Performance with Span and Memory

String Performance: Optimizing String Substring Extraction – Slicing vs. AsSpan()

Collection Performance: Memory Efficiency with AsMemory() in Byte Array Conversion

String Performance: Appending a Character using the StringBuilder

Collection Performance: Comparing Key Search Methods in Dictionaries

General Performance Tip: Comparing ComputeHash(), HashData(), and TryHashData() Methods

256 Seconds with dotNetDave: Be careful using ContainsKey() with Dictionary Types

Code It Any Way You Want: Optimizing Span Operations – Clear vs. Fill

Microsoft .NET Code Analysis: Improving Code Quality with Exception Throw Helpers

Microsoft .NET Code Analysis: Avoid Using Constant Arrays as Arguments

String Performance: Comparing Strings with Globalization

Collection Performance: Adding Items To a Dictionary

Microsoft .NET Code Analysis: Optimizing String Methods for Performance – Leveraging Character Over String for Enhanced Efficiency

Microsoft .NET Code Analysis: UTF-7 Encoding Is Insecure

Microsoft .NET Code Analysis: Optimizing Collection Examination

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