What’s New In .NET 9? Top Features and Updates Not To Miss

Quick Summary

Table of Contents

Introduction

Released in November 2024, .NET 9 introduces significant performance improvements and better runtime optimizations. Developers can now benefit from enhanced JIT compilation, improved garbage collection, and stronger security protocols. These updates reduce memory fragmentation, optimize CPU usage, and ensure faster application startup times. With new features in C# 13, along with improvements in Blazor and .NET MAUI, this version is designed to enhance productivity and streamline software development.

What’s New in .NET 9?

.NET 9 provides major runtime upgrades, C# 13 enhancements, and AI-powered capabilities. The JIT compiler has been optimized, garbage collection is more efficient, and security has been strengthened with Control-Flow Enforcement Technology (CET). Additionally, .NET MAUI gets UI improvements, while ASP.NET Core offers faster rendering and enhanced scalability for web apps.

Performance and Runtime Enhancements

.NET 9 delivers substantial runtime improvements in JIT compilation, garbage collection, and application startup, making execution more efficient. With better CPU utilization, optimized memory management, and enhanced ARM64 support, applications experience lower latency, faster load times, and improved performance under high workloads.

• JIT compilation now uses tiered optimizations, generating more efficient machine code for better execution speed and reduced CPU overhead.
• Garbage Collection (GC) introduces dynamic heap resizing, improving allocation strategies and reducing fragmentation for long-running applications.
• Application startup benefits from optimized cold-start execution, reducing memory overhead and improving initialization times.
• ARM64 support includes architecture-specific optimizations, enhancing power efficiency and execution speed on ARM-based devices.
• New diagnostics tools provide low-level performance insights, allowing real-time profiling, execution flow analysis, and memory usage tracking.

C# 13 Features

C# 13 introduces better memory management, improved concurrency, and syntax simplifications. params collections allow passing multiple arguments more efficiently without manual array instantiation. The new lock type provides better thread synchronization in multi-threaded environments. Implicit indexer access removes boilerplate code in object initializers.

• params collections simplify passing multiple arguments.
• New lock type improves concurrent execution.
• \e escape sequence introduces better string formatting.
• Implicit indexer access reduces code redundancy.
• ref struct types now support interfaces for memory efficiency.

.NET Libraries & APIs Enhancements

.NET 9 enhances core libraries by optimizing serialization, LINQ, cryptography, and reflection. These improvements make applications faster, more secure, and more efficient in handling large datasets, complex queries, and cryptographic operations while ensuring compatibility with modern development needs.

• System.Text.Json adds JSON schema export, improving validation and data exchange.
• BinaryFormatter is removed, eliminating security risks in serialization.
• LINQ gains CountBy and AggregateBy, enhancing query performance.
• Regex processing is faster, improving text-matching efficiency.
• Logging with source generators reduces runtime overhead, compiling logs at build time.
• KMAC, ChaCha20-Poly1305, and HashData strengthen encryption, ensuring secure cryptographic operations.
• Ref struct support improves memory efficiency, reducing heap allocations.
• Networking now supports HTTP/3, reducing latency and improving performance.
• Reflection is optimized, speeding up metadata access.

ASP.NET Core & Blazor Enhancements

Blazor and ASP.NET Core in .NET 9 see performance improvements, faster rendering, and better static file caching. Hybrid Blazor support enables seamless server-side and client-side rendering. Automatic reconnection prevents session loss after network failures, making real-time applications more stable and responsive.

• Static asset delivery is optimized, improving caching and reducing load times.
• MapStaticAssets simplifies static file management, enhancing performance.
• Blazor Hybrid rendering improves UI responsiveness, offering better client-server interactions.
• Server-side reconnection is more reliable, preventing session loss on network disruptions.
• SignalR supports WebSocket compression, reducing data transfer overhead for real-time apps.
• Minimal APIs add TypedResults and better OpenAPI support, improving API development.

.NET MAUI - Multi-Platform App UI

.NET MAUI introduces better UI performance, improved cross-platform support, and new controls. The TitleBar control allows UI customization on Windows, while HybridWebView makes embedding JavaScript frameworks like React and Angular easier. These updates enhance native app performance and developer flexibility.

• Optimized UI performance improves rendering speeds.
• New TitleBar control enhances Windows desktop UI.
• HybridWebView control enables JavaScript integration.

Entity Framework Core 9

EF Core 9 features query optimizations, better database connections, and improvements to Azure Cosmos DB. Query execution has been streamlined, making LINQ-to-SQL translations faster and more accurate. These enhancements improve database performance, reducing query response times in high-load applications.

• Enhanced Azure Cosmos DB support for NoSQL workloads.
• Optimized query execution improves database speed.
• Improved LINQ-to-SQL translation reduces query latency.

Windows Presentation Foundation (WPF) & Windows Forms Updates

.NET 9 improves desktop UI with Fluent Design support, typography enhancements, and dark mode integration. Windows Forms introduces asynchronous dialogs, improving UI responsiveness. These updates bring modern UI features to Windows-based applications, making them more visually appealing and efficient.

• Fluent theme and dark mode support improved UI design.
• Typography updates enhance text rendering.
• Asynchronous dialogs (Form.ShowAsync, Form.ShowDialogAsync).

.NET SDK & Developer Productivity Enhancements

.NET 9 adds better debugging tools, improved workload management, and faster testing capabilities. Workload Sets help developers lock dependencies, ensuring stability. MSBuild Script Analyzers detect issues earlier. The dotnet workload history command provides visibility into updates, reducing dependency conflicts.

• Workload Sets allow version locking, preventing unexpected updates and ensuring stability.
• NuGet security audits detect vulnerabilities, helping developers maintain secure dependencies.
• MSBuild performance is improved, reducing build times and optimizing dependency resolution.

Cloud-Native Application Enhancements

.NET 9 enhances support for cloud-native applications, making deploying, scaling, and monitoring applications in Kubernetes, Docker, and serverless environments easier. It introduces smaller, more efficient container images, better integration with OpenTelemetry, and performance optimizations for microservices. These improvements enhance observability, resource management, and deployment flexibility.

• Optimized ASP.NET Core performance for Kubernetes and Docker.
• Smaller container images improve startup time and reduce resource usage.
• Built-in OpenTelemetry support enhances logging and monitoring.
• Improved microservices support optimizes inter-service communication.

AI & Machine Learning Enhancements (ML.NET 4.0)

.NET 9 includes ML.NET 4.0, bringing better performance, enhanced model training, and improved cloud integration. It optimizes TensorPrimitives for high-speed numerical computations, improves ONNX model execution, and refines data processing pipelines. These updates make AI and ML applications faster, more efficient, and easier to deploy in cloud environments.

• ML.NET 4.0 improves ONNX model execution, reducing inference latency.
• TensorPrimitives optimizations accelerate numerical computing, improving AI workloads.
• Training pipelines are more efficient, optimizing model training and deployment.
• Seamless cloud-based AI integration simplifies scalable machine learning applications.

.NET Aspire Enhancements

.NET 9 enhances cloud-native development with better scalability, monitoring, and microservices support. These improvements simplify distributed application management, Azure integration, and observability, making cloud deployments more efficient and resilient.

• Simplified SDK installation streamlines Aspire setup and configuration.
• Dashboard improvements enhance monitoring, providing better resource tracking.
• Resource lifecycle management optimizes auto-scaling, improving system efficiency.
• Optimized telemetry improves logging, offering real-time performance insights.
• Persistent containers retain state, ensuring reliability in cloud-based applications.
• Azure Functions support enables serverless computing, improving cloud-native workflows.
• Customizable Azure Container Apps enhance deployment control, making scaling easier.

.NET 8 vs .NET 9 - A Quick Comparison

.NET 9 builds on .NET 8 with better performance, AI enhancements, and security updates. While .NET 8 introduced Native AOT, .NET 9 improves JIT compilation and garbage collection for better efficiency. Blazor Hybrid rendering, C# 13 concurrency updates, and stronger cryptographic security make .NET 9 a more robust framework.

Conclusion