I think C#/.NET has more performance-oriented affordances than Java:

- It supports structs, and unboxable structs called "ref structs". They let you to avoid GC/heap-alloc for small data structures with clear ownership semantics.

- It uses type reification for generics instead of type erasure. Combined with value-types, this can produce very optimized code. The downside is larger binary sizes.

- It allows unsafe programming with pointer arithmetic where performance is truly critical. This is where C# is closer to C/C++ than Java.

- Supports native compilation to a target architecture. This lets you avoid JIT overhead and lets you ship self-contained binaries (like Go).

- .NET supports source generators which can let you keep maintainable code and generate an optimized one.

Performance aside, C# is a very pleasant language to use, and .NET is a delightful runtime. I'd say give it a try and see it for yourself.

It runs on Windows, Mac, and Linux x86/x64/Arm64

The main target is enterprise software systems and web backends. Asp.Net is a very mature framework for Web APIs and MVC applications.

Entity Framework is a decent ORM solution supporting several popular DBs with tools for code generation and migrations, and LINQ is a complementary query language that is useful for in-memory collection operations as well as db queries.

And I think the largest value is in the NuGet software library ecosystem, things like MassTransit for service bus and queue communication and many many others.

It’s a well-supported ecosystem of first party and third party software with a lot of modern features, but definitely still in the realm of managed runtimes so not a competitor to C, Rust, etc.

> Asp.Net is a very mature framework for Web APIs and MVC applications.

*ASP.NET Core

True, the non-Core versions really aren’t worth considering for a new dev entering the ecosystem, and MS has made it clear that .NET Core is .NET going forward.

ASP.NET is rumored to drop the "Core" name somewhere in major version 7/8/9, just as .NET dropped "Core" in .NET 5, which is a higher version number than both sides of the fork. There was briefly an ASP.NET 6 (technically, the baroque "ASP.NET 5 MVC 6"). There's never yet been a version higher than that. I think part of the hold up there were some builds of the old Entity Framework made to version 8 or 9, and ASP.NET is not likely to drop "Core" until EF Core is able to drop "Core"?

EF Core is dropping Core on version 7, so November.

I've spent most of my career in Java and there are certainly some things that C# (I know, somewhat tangential to .NET at this point, but still relevant) does better. E.g. if I want to use declarative style to describe something I want out of a data structure, I'd much rather use LINQ than Streams.

It's broadly in the same ballpark as Java, but with more language features (e.g. sequence comprehensions, pattern matching), and it offers some low-level features like raw pointers and spans for when you want performance or interop with C.

I don't think it offers anything compelling for cross-platform web/network services that Go does not.

Microsoft relies on "fire and motion"¹ to sell to developers, and typically reimplements instead of working with open source projects.

Recent example: only Visual Studio 2022 supports .NET 6, time to upgrade.

¹ https://www.joelonsoftware.com/2002/01/06/fire-and-motion

Or you can use VSCode, Rider, or your text editor of choice plus the cli tools.