Breaking: Microsoft Ships .NET 11 Preview 4 with Major Performance Upgrades and New Developer Tools

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Microsoft Releases .NET 11 Preview 4

Microsoft has officially released .NET 11 Preview 4, bringing sweeping improvements to the runtime, SDK, libraries, ASP.NET Core, .NET MAUI, C#, and Entity Framework Core. The update is now available for download and testing.

This preview represents a significant step toward the final .NET 11 release, with a focus on performance, cross-platform tooling, and developer productivity.

Key Highlights

Libraries: Process Gets Historic Overhaul

The System.Diagnostics.Process class receives its biggest update in years. Additionally, new span-based APIs for Deflate, ZLib, and GZip encoding/decoding are introduced. Floating-point hex formatting and parsing are now supported, and System.Text.Json sees multiple enhancements.

“These library updates are about modernizing core .NET capabilities and making high-performance scenarios easier for developers,” said a .NET team spokesperson.

Runtime: Async Compilation and JIT Optimizations

Runtime libraries are now compiled with runtime-async, enabling better asynchronous performance. Just-in-time (JIT) compiler optimizations and hardware intrinsic improvements boost code generation quality.

SDK: Device Selection, Fish Shell Completions, and OpenTelemetry

dotnet watch now supports device selection for .NET MAUI and mobile projects. Fish shell completions join existing Bash, Zsh, and PowerShell support. Commands like dotnet reference fall back to the current directory automatically. CLI telemetry shifts from Application Insights to OpenTelemetry.

C#: Clearer Diagnostics and Compilation Cache

Misplaced #! shebang directives now produce clearer diagnostic messages. An opt-in compilation cache for the VBCSCompiler build server reduces repeated builds.

ASP.NET Core: HTTP QUERY, Blazor Improvements, MCP Server Template

Generated OpenAPI documents now include the HTTP QUERY method. Blazor gets SupplyParameterFromTempData and server-initiated circuit pausing. The MCP Server template ships directly with the .NET SDK.

.NET MAUI: dotnet watch for Android and iOS

dotnet watch now works for both Android and iOS targets in .NET MAUI applications, enabling faster iteration during mobile development.

Entity Framework Core: SQL Server 2025 Vector Search and JSON Mapping

Approximate vector search for SQL Server 2025 is now supported. JSON mapping is fully integrated into the relational model. Temporal period properties can map to CLR properties, and dotnet ef reads defaults from a configuration file.

Background

.NET 11 is the next major version of Microsoft’s open-source, cross-platform development platform. Preview releases allow developers to test new features and provide feedback before the final release. Preview 4 includes changes across all major components.

This release continues Microsoft’s tradition of shipping regular previews to gather community input and stabilize APIs. The .NET team has emphasized performance, modern patterns, and mobile improvements in this cycle.

What This Means

For enterprise developers, the Process library updates simplify systems integration. The new compression APIs offer better memory efficiency. ASP.NET Core’s MCP Server template lowers the barrier for building custom tooling. .NET MAUI developers gain parity with web and desktop hot-reload workflows.

“This preview demonstrates our commitment to making .NET faster and more versatile, whether you’re building cloud services, mobile apps, or desktop tools,” the spokesperson added.

Get Started

Developers can download .NET 11 Preview 4 from the official .NET site. Windows users with Visual Studio should install the latest Visual Studio 2026 Insiders build. Visual Studio Code with the C# Dev Kit extension also supports the preview.

Full release notes for each component are linked from the announcement: Libraries, Runtime, SDK, C#, ASP.NET Core, .NET MAUI, and Entity Framework Core.

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