1. Native AOT Gets Even Better
Native AOT (Ahead-of-Time compilation) is one of the biggest wins in .NET 9. Apps can now be compiled directly to native code, delivering:
Much faster startup times
Lower memory usage
Smaller deployment artifacts
This makes .NET 9 perfect for microservices, serverless workloads, and container-heavy environments. AOT is now more stable, works with more project types, and offers better diagnostics than previous releases.
2. ASP.NET Core Performance Boosts
.NET 9 gives ASP.NET Core a major refresh, especially around speed and flexibility.
Key improvements:
New Output Caching middleware for super-fast response caching
Smarter and more powerful Minimal APIs, including automatic metrics + better DI
Improved HTTP/3 support
The new Blazor United model blends server-side and WebAssembly into a seamless experience
3. Runtime & Performance Enhancements
Performance continues to be a major focus in .NET 9.
You get:
Smarter Garbage Collection that adapts to app load
Loop execution optimizations (great for AI/data workloads)
Faster tiered JIT compilation
Reduced latency for Large Object Heap allocations
4. Better AI & ML Support
AI development becomes smoother in .NET 9 thanks to:
Faster integration with ONNX Runtime
Improved vector math through System.Numerics
Performance boosts for ML.NET
This means faster model inference and smoother AI features in your .NET applications.
5. Built for Cloud-Native Apps
Whether you deploy on Azure, AWS, or GCP, .NET 9 comes packed with cloud-first improvements:
Smaller Docker images (up to 30% smaller)
Better Kubernetes readiness
Stronger OpenTelemetry support
Smarter trimming for minimal deployments
Your cloud apps will start faster, cost less, and scale better.
6. C# 13 Quality-of-Life Features
C# 13 arrives alongside .NET 9 with subtle but meaningful improvements:
params now supports multiple collection types
New implicit indexing options
ref struct is more flexible (can implement interfaces + be generic arguments)
Partial members for cleaner code organization
These features make everyday C# coding cleaner and more expressive.
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7. .NET MAUI Gets More Stable
Developers building cross‑platform apps benefit from:
Faster build times
Less UI thread blocking
More native behavior across Android/iOS/macOS/Windows
.NET 9 makes MAUI feel significantly more polished.
8. Library Improvements (System.Text.Json + More)
.NET 9 updates core libraries with better:
JSON serialization performance
Record and immutable type handling
Feature switches for library-level toggles
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