Some improvements - C#

Very nice comparisons. Here are some improvements that can be made in C#

- Some cases use Span or Memory
[Link - Span, Memory](https://www.codemag.com/Article/2207031/Writing-High-Performance-Code-Using-SpanT-and-MemoryT-in-C)

- Some cases use ValueTask instead of Task
[Link - ValueTask](https://developpaper.com/how-to-use-valuetask-in-c/)

- For C# use Source Generator for **Json** (example below) and if possible bytes instead of string.

```
[JsonSerializable(typeof(Person))]
internal partial class MyJsonContext : JsonSerializerContext
{
}
```

```
Person person = new() { FirstName = "Jane", LastName = "Doe" };

byte[] utf8Json = JsonSerializer.SerializeToUtf8Bytes(person, MyJsonContext.Default.Person);

person = JsonSerializer.Deserialize(utf8Json, MyJsonContext.Default.Person):
```
[Link - Source Generator NET 6](https://devblogs.microsoft.com/dotnet/try-the-new-system-text-json-source-generator/)