What’s new in .NET 9?

.NET 9 has arrived, introducing a range of new features and enhancements designed to boost performance, streamline development, and expand the capabilities of its frameworks. As developers, we’re always looking for ways to optimize our workflow and create high-performance applications.

We’ll dive into the standout features of .NET 9, covering key areas such as the .NET runtime, libraries, SDK, EF Core, and ASP.NET Core. We’ll also touch on updates in C# 13. Whether you’re developing for web, desktop, or mobile platforms, .NET 9 has something valuable to offer.

.NET libraries

.NET 9 brings a suite of new and improved libraries to streamline development, with significant advancements in areas like cryptography, file I/O, and JSON serialization.

Cryptography Enhancements: The cryptography library now includes support for hardware-accelerated algorithms. This enables operations like hashing and encryption to utilize hardware instructions, delivering improved performance.

using System.Security.Cryptography;

var data = Encoding.UTF8.GetBytes("Hello, .NET 9!");
var hash = SHA256.HashData(data);
Console.WriteLine(Convert.ToBase64String(hash));

This hashing example showcases the use of the cryptography library, leveraging hardware acceleration for improved performance.

File I/O Enhancements: .NET 9 introduces optimized file reading and writing, offering improved support for asynchronous operations. These enhancements are especially beneficial when working with large files or managing multiple file operations concurrently.

using (FileStream fs = new FileStream("example.txt", FileMode.Open, FileAccess.Read, FileShare.Read, 4096, true))
{
    byte[] buffer = new byte[fs.Length];
    await fs.ReadAsync(buffer, 0, buffer.Length);
}

.NET Runtime

Enhanced Runtime in .NET 9:
At the heart of .NET 9 lies its upgraded runtime, delivering notable performance improvements. Key advancements in Just-In-Time (JIT) compilation, garbage collection (GC), and native interoperability have contributed to faster application execution and reduced memory usage.

Optimized JIT Compilation:
The JIT compiler in .NET 9 has been fine-tuned to provide quicker startup times and improved efficiency. By leveraging tiered compilation more effectively, applications benefit from reduced initial overhead while ensuring critical methods are fully optimized during execution.

public static int SumArray(int[] arr)
{
    return arr.Sum();
}

This straightforward code snippet takes advantage of faster JIT compilation in .NET 9, with performance gains that become even more evident in large-scale applications.

Garbage Collection (GC): The garbage collector in .NET 9 has been refined to deliver improved performance, particularly in applications with significant memory demands. Enhancements to large object heap (LOH) allocations help reduce latency, boosting real-time performance in memory-intensive environments.

.NET SDK

The .NET 9 SDK introduces a range of enhancements to streamline project management and development workflows. One key feature is unified package management, which simplifies handling dependencies and multiple package sources in complex solutions.

Multi-Framework Targeting:
With improved support for multi-targeting, the SDK makes it easier to build libraries compatible with various .NET versions and platforms, including Xamarin and Mono. This enhancement allows developers to maintain flexibility and efficiency across diverse project requirements.

<PropertyGroup>
 <TargetFrameworks>net9.0;netcoreapp3.1</TargetFrameworks>
</PropertyGroup>

This multi-targeting configuration enables your library to remain compatible with an older version of .NET while also leveraging the new features introduced in .NET 9.

ASP.NET Core

ASP.NET Core remains the leading web framework for .NET developers, and .NET 9 introduces several new features to further enhance the web development experience.

Blazor Server Improvements:
Blazor Server has been optimized to reduce latency and improve responsiveness, particularly in high-latency environments. These enhancements make Blazor applications more scalable and responsive, offering a smoother user experience.

@page "/fetchdata"
@inject HttpClient Http

@if (forecast is null)
{
    <p>Loading...</p>
}
else
{
    <table class="table">
     <thead>
      <tr>
       <th>Date</th>
       <th>Temp (C)</th>
       <th>Summary</th>
      </tr>
     </thead>
     <tbody>
      @foreach (var f in forecast)
         {
           <tr>
            <td>@f.Date</td>
            <td>@f.TemperatureC</td>
            <td>@f.Summary</td>
           </tr>
         }
     </tbody>
    </table>
}

This Blazor Server example illustrates how easily you can create fast and responsive web pages with .NET 9.

EF Core 9

EF Core has undergone significant updates in .NET 9, with key improvements such as enhanced performance for bulk operations, better handling of complex queries, and expanded support for various database providers. These updates aim to streamline development and optimize database interactions.

using var context = new BloggingContext();
var blogs = await context.Blogs
    .Where(b => b.Rating > 3)
    .ToListAsync();

In this code example, the enhanced performance of EF Core enables faster querying, particularly when dealing with larger datasets.

C# 13

.NET 9 introduces C# 13, bringing a host of improvements that make the language more powerful and easier to use. Notable features include enhanced pattern matching, support for default interfaces, and improvements to record types, all designed to simplify coding and boost productivity.

public record struct Point(int X, int Y);

var point = new Point(3, 4);
Console.WriteLine(point.X);  // Output: 3

Feature Comparison: .NET 8 vs .NET 9

Here’s the table with the rows jumbled:

Feature	.NET 8	.NET 9	Explanation
EF Core	Standard performance.	Bulk operation performance boost.	Faster bulk operations for large datasets.
Garbage Collection	Basic optimizations.	Improved LOH allocation.	Enhanced memory management and reduced latency.
Blazor Server	Initial support.	Latency and scalability improvements.	Better handling of high-latency environments.
.NET MAUI	Early stages.	Improved single-project support.	Easier cross-platform development with a unified structure.
Cryptography Library	Limited hardware support.	Full hardware acceleration.	Hardware-accelerated cryptography for faster operations.
JIT Compilation	Tiered JIT, optimized.	Faster startup, further optimized.	Faster startup times and method-level optimization.

Conclusion

.NET 9 marks a major leap forward for developers, introducing notable improvements in performance, tools, and features that make development more efficient. Whether you’re building web applications with ASP.NET Core, working on cross-platform projects using .NET MAUI, or developing data-heavy applications with EF Core, .NET 9 offers valuable enhancements. Upgrading from .NET 8 to .NET 9 brings practical benefits, improving both the overall developer experience and application performance. With faster startup times, better memory management, and new hardware acceleration, .NET 9 makes it easier to create high-performance, scalable applications.