There are many important improvements in .NET 5.0:
- .NET 5.0 is already battle-tested by being hosted for months at dot.net and Bing.com (version).
- Performance is greatly improved across many components and is described in detail at Performance Improvements in .NET 5.0, Arm64 Performance in .NET 5.0, and gRPC.
- C# 9 and F# 5 offer new language improvements such as top-level programs and records for C# 9, while F# 5 offers interactive programming and a performance boost for functional programming on .NET.
- .NET libraries have enhanced performance for Json serialization, regular expressions, and HTTP (HTTP 1.1, HTTP/2). They are also are now completely annotated for nullability.
- P95 latency has dropped due to refinements in the GC, tiered compilation, and other areas.
- Application deployment options are better, with ClickOnce client app publishing, single-file apps, reduced container image size, and the addition of Server Core container images.
- Platform scope expanded with Windows Arm64 and WebAssembly.