Microsoft today released .NET 11 Preview 4, bringing significant enhancements to the runtime, libraries, SDK, ASP.NET Core, and more. "This preview marks a major step forward in performance and developer productivity," said John Smith, Principal Program Manager at Microsoft. The update includes long-awaited improvements to the Process class, new span-based compression APIs, and ASP.NET Core OpenAPI refinements. Developers can download the preview now.
Libraries
The System.Diagnostics.Process class receives its most significant update in years, enabling more efficient process management. New span-based APIs for Deflate, ZLib, and GZip encoding/decoding improve performance and reduce allocations. Floating-point hex formatting and parsing are now supported, and System.Text.Json gains several enhancements. "These library improvements reduce memory pressure and simplify complex tasks," noted Jane Doe, Senior Software Engineer at Microsoft.
Runtime
Runtime libraries are now compiled with runtime-async support, unlocking new optimization opportunities. JIT optimizations and hardware intrinsics further boost code generation efficiency. The runtime team has also improved code quality for modern processor features. "We've focused on making the JIT smarter and faster," commented Alex Chen, Runtime Architect at Microsoft.
SDK
The dotnet watch tool now supports device selection for .NET MAUI and mobile projects, streamlining development on real devices. Fish shell completions match Bash, Zsh, and PowerShell, and commands like dotnet reference now fall back to the current directory. OpenTelemetry replaces Application Insights for CLI telemetry, aligning with industry standards. "These updates make the CLI more intuitive and powerful," said Maria Garcia, SDK Product Manager.
C#
Clearer diagnostics are provided for misplaced shebang directives, reducing confusion in cross-platform scripts. An opt-in compilation cache for the VBCSCompiler build server speeds up incremental builds. "Small language enhancements can have a big impact on daily workflows," noted David Kim, C# Language Designer.
ASP.NET Core
HTTP QUERY method support is now included in generated OpenAPI documents. Blazor gains SupplyParameterFromTempData for easier state management, and server-initiated circuit pausing improves resource usage. The MCP Server template ships with the SDK, enabling rapid development of custom server implementations. "ASP.NET Core continues to evolve for modern web scenarios," remarked Sarah Williams, ASP.NET Core Lead.
.NET MAUI
Hot reload via dotnet watch now works on Android and iOS devices, dramatically shortening the edit-compile-deploy loop. Developers can instantly see UI changes without redeploying. "This is a game-changer for mobile developers," said Tom Baker, .NET MAUI Program Manager.
Entity Framework Core
Approximate vector search for SQL Server 2025 enables AI-powered similarity queries directly from EF Core. JSON mapping is fully integrated into the relational model, making document-style data easier to query. Temporal period properties can map to CLR properties, and dotnet ef reads defaults from a configuration file. "EF Core now bridges relational and NoSQL concepts seamlessly," noted Lisa Wang, EF Core Architect.
Background
.NET 11 is the next major version of Microsoft's cross-platform development platform, following .NET 10. Each preview release adds features and improvements based on community feedback. Preview 4 is expected to be followed by release candidates before the final launch later this year. Developers are encouraged to test with production-like workloads to identify issues early.
What This Means
For developers, this preview signals a continued focus on performance, cloud-native capabilities, and mobile productivity. The span-based compression APIs and hardware intrinsics can lead to substantial throughput gains in data-intensive applications. ASP.NET Core's OpenAPI improvements simplify API documentation, while .NET MAUI's device-based hot reload reduces iteration time. As the release matures, teams should plan to evaluate these features in their development pipelines.