What’s new in .NET 9: Innovation, Performance, and AI Integration

The release of .NET 9 marks a major milestone for developers and businesses seeking a modern, secure, and high-performing development platform. With significant enhancements across the entire .NET ecosystem, this update represents Microsoft’s commitment to transforming how developers create, deploy, and maintain applications. From performance upgrades and tool advancements to new AI integrations, .NET 9 has something for every developer.

Key Performance Enhancements: Faster Apps, Lower Memory Usage

Performance remains a focal point for .NET releases, and .NET 9 pushes the boundaries even further. This release includes over 1,000 performance-related improvements, delivering a faster and more efficient developer experience.

• Adaptive Server GC (Garbage Collection): Previously, users needed to balance Workstation and Server GC based on memory and CPU resources. .NET 9 introduces adaptive Server GC, which tailors memory usage based on application demands, optimizing performance in environments with fluctuating memory needs. The result? Greater efficiency for cloud apps and high-core-count systems.
• Vectorization Improvements: The runtime has been optimized to support new silicon architectures such as Arm64 SVE and Intel AVX10. Enhanced loop vectorization and bounds checking accelerate workloads, while exceptions now execute 50% faster thanks to the same model used by Native AOT.
• Optimized LINQ Operations: Common LINQ operations, such as Take and DefaultIfEmpty, are now up to 10 times faster. By reducing the overhead of these operations, developers can expect better overall performance in data-intensive applications.

The cumulative impact of these improvements is reflected in benchmark results, including a significant 15% increase in RPS (Requests per Second) and a 93% decrease in memory usage.

.NET Aspire: Building Production-Ready Apps with Ease

.NET Aspire is a comprehensive toolkit designed to simplify the development of robust, production-ready applications. With seamless integration into existing .NET projects, Aspire offers new tools, templates, and packages to enhance observability, deployment, and more.

• Improved Telemetry and Metrics Dashboard: .NET Aspire’s enhanced telemetry tools streamline monitoring and debugging applications, making it easy for developers to gain actionable insights.
• New APIs and Resource Management: Features like WaitFor provide better control over resource startup, while the ability to start and stop resources from the dashboard improves overall app management.
• Integration with Azure Services: From Azure Container Apps to Azure Functions, .NET Aspire enhances deployment scenarios, ensuring seamless integration into the Azure ecosystem.

Microsoft’s internal adoption of Aspire, including teams like Xbox and Copilot, speaks to its versatility and capability to accelerate app development across diverse scenarios.

AI-Powered Capabilities: Bringing Intelligence to .NET

The .NET 9 release continues to expand the framework’s AI capabilities, allowing developers to create intelligent applications with greater ease and flexibility. This includes a robust ecosystem of AI libraries, seamless integrations, and more intuitive APIs.

• Semantic Kernel and VectorData Extensions: In collaboration with Microsoft.Extensions.AI, developers can interact with both small and large language models, vector stores, and middleware through a unified set of C# abstractions. This integration simplifies the adoption of AI-driven functionality.
• Enhanced Tokenization Libraries: For those building AI models, Microsoft.ML.Tokenizers now includes improved support for popular model families such as GPT, Llama, and more. This, combined with new tokenization algorithms, makes leveraging cutting-edge language processing capabilities easier.

Overview of New Features in ASP.NET Core in .NET 9

.NET 9 brings several exciting updates, particularly in ASP.NET Core, aimed at improving performance, scalability, and ease of development. Here’s a breakdown of the key features that developers can look forward to:

1. .NET MAUI – Enhancing Multi-Platform App Development

.NET MAUI continues to evolve as the go-to framework for building cross-platform applications for mobile and desktop devices. With .NET 9, it delivers enhanced performance, reliability, and deeper integrations, ensuring developers can easily create stunning apps for Android, iOS, macOS, and Windows from a single codebase. Key highlights include:

• Improved Performance: Major performance boosts across various controls, including updates to CollectionView and CarouselView for iOS & Mac Catalyst.
• Smaller Apps: Native AOT (Ahead of Time) and trimming enhancements allow the creation of faster, smaller applications.
• Community Contributions: Contributions from Syncfusion, a leading .NET component vendor, have significantly enriched the framework.
• Expanded Template: The introduction of a new project template featuring 14 free, open-source Syncfusion controls and other community libraries to jumpstart development.

2. Windows Development with .NET 9

.NET 9 enhances Windows development, enabling developers to access the latest OS features and improve performance. Whether you’re developing with WinUI 3, WPF, or WinForms, .NET 9 offers a seamless experience with several new features:

• Native AOT Support for WinUI 3: This boosts performance for smaller, more efficient apps.
• Fluent UI Enhancements: Modern theming improvements for WPF apps, making them look more contemporary and user-friendly.
• Dark Mode for WinForms: A new dark mode support to align with modern app design standards.

3. C# 13 and F# 9 Enhancements

C# 13 and F# 9 bring several improvements to streamline development, boost performance, and introduce new features:

• C# 13: Introduces improvements like enhanced use of the params modifier, enabling the use of broader collection types, and better performance for ref struct values.
• F# 9: Focuses on performance and safety, including optimizations like integral ranges, improved diagnostics, and new random functions for collections.

4. Enhanced Developer Tools

.NET 9 introduces a range of improvements to Visual Studio 2022 and Visual Studio Code, making them more powerful and efficient:

• Visual Studio 2022: The new version boasts better performance, improved debugging, and deeper cloud integrations.
• CLI Enhancements: The .NET CLI is more secure and productive with features like clickable links, color-coded outputs, and improved logging.

5. NuGet Ecosystem Improvements

NuGet, the package manager for .NET, continues to grow rapidly. In .NET 9, developers will benefit from:

• Improved Security: Features like vulnerability auditing for top-level and transitive dependencies to ensure secure package management.
• Enhanced Ecosystem: With over 420,000 packages and 570 billion downloads, the NuGet ecosystem has never been more robust, contributing significantly to faster development cycles.

Notable Features in .NET 9:

• Improved cross-platform support with .NET MAUI.
• Enhanced WinUI 3 and WPF support for modern, efficient Windows apps.
• C# 13 and F# 9 introduce new language features and performance optimizations.
• Visual Studio 2022 brings significant performance and cloud integration upgrades.
• NuGet security updates ensure safer package management with auditing features.

Streamlined Web Development with ASP.NET Core and Blazor

Building web applications has never been easier or more efficient, thanks to enhancements in ASP.NET Core and Blazor. .NET 9 offers notable performance, accessibility, and security improvements, creating a comprehensive framework for modern web apps and scalable backend services.

• Optimized Static Files Handling: Static assets like JavaScript and CSS files are now fingerprinted during the build and compressed using Brotli for more efficient deployment. This ensures faster load times and minimizes the burden on servers.
• Improved Blazor Components: Blazor has been optimized to allow runtime detection of component render modes, providing a more dynamic user experience. Additionally, interactive server rendering has been upgraded for faster reconnections and friendlier UI during network disruptions.

Developer Productivity Gains with GitHub Copilot

.NET 9 introduces a range of productivity enhancements for developers using GitHub Copilot, further simplifying the coding, debugging, and testing process.

• AI-Powered Variable Inspection: Integrated AI-powered debugging tools streamline variable inspection during development.
• Enhanced LINQ Expressions Visualization: The IEnumerable visualizer now supports AI-driven LINQ editable expressions, making it easier to analyze and modify data queries.
• Improved C# Code Completions: Copilot now leverages additional context from source files, providing more accurate code suggestions.

Full-Stack Development with ASP.NET Core

Developers looking to build full-stack web apps can leverage ASP.NET Core’s improved features in .NET 9. The framework now offers expanded support for ahead-of-time compilation, improved monitoring, and faster performance, all while ensuring security remains a top priority.

• Built-In OpenAPI Support: API developers benefit from native support for OpenAPI document generation, enabling optimized and scalable service creation.
• Endpoint Routing and Static File Improvements: Static assets can now use endpoint-aware features like per-endpoint authorization, further enhancing security and functionality.

Conclusion: A Unified Platform for Modern App Development

The launch of .NET 9 solidifies Microsoft’s vision of a unified, performant, and intelligent platform for app development. With groundbreaking performance enhancements, developer-friendly tools, and cutting-edge AI integrations, .NET 9 provides everything needed to build modern, scalable applications. Developers can look forward to a more productive and innovative development experience backed by a vibrant ecosystem and community-driven support.