Microsoft shipped .NET 10 Preview 1, introducing a raft of improvements and fixes across performance, libraries, and the developer experience.

The JIT compiler now optimizes array interface calls and enables stack allocation for small value type arrays, reducing heap usage. Enhanced cryptographic support includes improved certificate handling and direct PEM data reading. The new CompareOptions.NumericOrdering improves string comparisons, and ZipArchive sees performance and memory enhancements. ASP.NET Core adds OpenAPI 3.1 and YAML support, along with Blazor improvements like script asset handling and QuickGrid enhancements. EF Core 10 refines LINQ-to-SQL translation and introduces batch size control for async updates. These updates collectively enhance .NET's efficiency, security, and usability for modern development.

.NET runtime

The .NET 10 runtime has introduced new features and performance improvements, which have been updated for Preview 1. One of the main focuses for .NET 10 is to reduce the abstraction overhead of popular language features. In order to achieve this goal, the JIT's ability to devirtualize method calls has been expanded to cover array interface methods. This means that the JIT can now optimize code that loops over an array, even if there are virtual calls involved. Additionally, the JIT now has the ability to stack-allocate small, fixed-sized arrays of value types that do not contain GC pointers, further reducing the abstraction penalty of reference types.

Another new feature in .NET 10 is the support for Advanced Vector Extensions (AVX) 10.2 for x64-based processors. This is currently disabled by default as hardware supporting AVX10.2 is not yet available. Once it is available, the new intrinsics in the System.Runtime.Intrinsics.X86.Avx10v2 class can be tested. These updates and improvements are part of the ongoing efforts to achieve performance parity between different implementations in .NET 10.

ASP.NET Core

Changes in ASP.NET Core 10.0 include:

• Blazor: Added new features for Blazor, including the QuickGrid RowClass parameter and Blazor script serving as a static web asset.
• SignalR: Added new features for SignalR.
• Minimal APIs: Added new features for minimal APIs.
• OpenAPI: Added support for generating OpenAPI version 3.1 documents and serving the generated OpenAPI document in YAML format.
• Authentication and authorization: Added new features for authentication and authorization.
• Miscellaneous: Added better support for testing apps with top-level statements and a new helper method for detecting local URLs.

C# 14

C# 14 introduces several new features and enhancements to improve developer productivity and code quality. Some of the key updates include:

• nameof in unbound generics.
• Implicit span conversions.
• field backed properties.
• Modifiers on simple lambda parameters.
• Experimental feature - String literals in data section.