High Performance byte[] to Hex String Converter.

HexUtils.cs

public static class HexUtils
{
  public static string ToHexString(byte[] bytes)
  {
    return string.Create(bytes.Length * 2, bytes, (chars, buffer) =>
    {
      for (var i = 0; i < buffer.Length; i += 2)
      {
        var b = buffer[i / 2];
        chars[i] = GetHexChar(b / 16);
        chars[i + 1] = GetHexChar(b % 16);
      }
    });
  }

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  private static char GetHexChar(int i)
  {
    return i > 9
      ? (char)(i - 10 + 'a')
      : (char)(i + '0');
  }
}