is there a open source c# library with a gethashcode equivalent which is even faster than gethashcode() for strings? in csharp in csharp

One popular open source library that provides faster hashing for strings than GetHashCode() is CityHash. CityHash is a fast non-cryptographic hash function that produces well-distributed 64-bit hashes for strings.

You can use the CityHash.Net NuGet package to add CityHash to your C# project. Here's an example of how to use it:

main.cs
using Google.CityHash;

string myString = "example string";
ulong hash = CityHash.CityHash64(myString, (ulong)myString.Length);
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In this example, we first import the Google.CityHash namespace. We then define an example string and call the CityHash64 method to get the 64-bit hash code for the string.

Note that CityHash is not a drop-in replacement for GetHashCode(). It is designed to provide faster hash codes for strings specifically and may not work as well for other types of objects.