C# Optimizations

[jarnmo]

Hey! Always fun to see these comparisons :)

Couple tips for improving the .net version performance:

You're using structs as readonly so change struct to readonly struct. This helps the compiler do some additional optimizations.

You can improve the parsing performance and memory consumption probably by a lot by reading the file to a single string and then splitting it into (ReadOnly)Spans as much as possible rather than creating lots and lots of small strings.

You can also enable rigorous null safety by adding <Nullable>enable</Nullable> to your project file. Or by other means described here: https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references#nullable-contexts

[jarnmo]

Also for convenience you could use record structs and LINQ

So

public struct StopTimeResponse
{
  public string stop_id { get; }
  public string arrival_time { get; }
  public string departure_time { get; }
  public StopTimeResponse(string stopID, string arrival, string departure)
  {
    stop_id = stopID;
    arrival_time = arrival;
    departure_time = departure;
  }
}

into

public readonly record struct StopTimeResponse (string stopID, string arrival, string departure);

Also, in C# it's common to use PascalCase for public properties and methods.

LINQ: https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/query-syntax-and-method-syntax-in-linq

[theolivenbaum]

Pushed some changes on #15 that should help here!

[Andoreatta]

Also take a look at this.
https://devblogs.microsoft.com/dotnet/performance_improvements_in_net_7/