It's a heavily gamed benchmark, but TechEmpower Fortunes is pretty good at revealing the max throughput of a language runtime for "specially tuned" code (instead of idiomatic code).
I judge more idiomatic / typical code complexity by the length of stack traces in production web app crashes. Enterprise Java apps can produce monstrous traces that are tens of pages long.
ASP.NET Core 9 is a bit worse than ASP.NET Web Forms used to be because of the increased flexibility and async capability, but it's still nowhere near as bad as a typical Java app.
What matters in practical scenarios is that ASP.NET Core is significantly faster than Spring Boot. If you have a team willing to use ActiveJ or Vert.x, you are just as likely have a team willing to customize their C# implementation to produce numbers just as good at web application tasks and much better at something lower level. There are also issues with TechEmpower that make it highly sensitive to specific HW/Kernel/Libraries combination in ways which alter the rankings significantly. .NET team hosts a farm to do their own TechEmpower runs and it just keeps regressing with each new version of Linux kernel (for all entries), despite CPU% going down and throughput improving in separate more isolated ASP.NET Core evaluations. Mind you, the architecture of ASP.NET Core + Kestrel, in my opinion, leaves some performance on the table, and I think Techempower is a decent demonstration of where you can expect the average framework performance to sit at once you start looking at specific popular options most teams use.
No, records are a reduction in boilerplate for regular classes (the result also happens to be read-only — not deeply immutable, mind you). Value types are in the works:
Hmm looking at that it seems like being a struct type is a non-goals they seem to explicitly call out C# value types as a different thing...
Smaller objects from dropping identity is nice but it really doesn't seem like it gives you more explicit memory layout, lifecycle, c interop etc that C# has with their structs. Maybe I'm missing something.
Trying to write it as if it was a different language instead or, for whatever reason, copying the worst style a team could come up with does happen and must be avoided, but that’s user error and not a language issue. Also the tooling, especially CLI, is excellent and on par with what you find in Rust, far ahead of Java and C++.
If you link an example snippet of the type of code that gave you pause, I’m sure there is a better and more idiomatic way to write it.
C# is Java-but-with-lessons-learnt, and is significantly less verbose and "enterprisey" in typical usage.
Modern .NET 9 especially embraces compile-time code generation, a "minimal" style, and relatively high performance code compared to Java.
Even if the JVM is faster in benchmarks for hot loops, typical Java code has far more ceremony and overhead compared to typical C# code.