.NET 6 Released: The Fastest .NET Yet with C# 10

What happened

.NET 6 was released on November 8, 2021, according to the official announcement on the Microsoft .NET DevBlog by Richard Lander. The result of just over a year of work by the team and community, it was described as the fastest .NET yet and shipped as a long-term-support release supported for three years. It was the first release to natively support Apple Silicon (Arm64) and was also improved for Windows Arm64.

A unified platform

.NET 6 delivered a unified platform for browser, cloud, desktop, IoT and mobile apps, all using the same .NET libraries with easy code sharing. New capabilities became available to all app types at once, so code running in the cloud or on a mobile device behaved the same way. The release also laid groundwork for .NET Multi-platform App UI (.NET MAUI), which would follow a little later to enable a single project targeting desktop and mobile.

Performance and productivity

Performance was greatly improved across the board, with a new dynamic Profile-Guided Optimization (PGO) system delivering deep runtime optimisations and a rewritten FileStream making async file I/O on Windows several times faster and often allocation-free. Hot Reload let developers view changes without restarting a running app, supported in Visual Studio 2022 and the .NET CLI, and minimal APIs were introduced in ASP.NET Core to simplify building HTTP services.

Languages and new APIs

C# 10 added language improvements such as record structs, global using directives and new lambda capabilities, while F# 6 added task-based async and performance improvements. New APIs arrived for HTTP/3, JSON processing with a source generator, mathematics and direct memory manipulation, and security was strengthened with support for OpenSSL 3 and runtime defense-in-depth mitigations. The release comprised about ten thousand git commits.

Why it mattered

.NET 6 was a landmark LTS release that unified Microsoft's development platform and brought native Apple Silicon support, major performance gains and productivity features like Hot Reload and minimal APIs. It became a stable, long-supported foundation that many teams migrated to from .NET Core 3.1 and .NET 5.

Related on Skillo

See also: .NET 7's performance and C# 11.

Sources

• Announcing .NET 6 (Microsoft DevBlogs)

Published date reflects the original event date (2021-11-08). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.