StringBuilder should be used in CsQuery.HtmlParser.ExtensionMethods

[matt-psaltis]

There's other ways of achieving this but in keeping with the existing method format...
The existing result += text[i]; kills performance when parsing larger html blocks.

    public static string SubstringBetween(this char[] text, int startIndex, int endIndex)
    {
        var result = new StringBuilder();
        for (var i = startIndex; i < endIndex; i++)
        {
            result.Append(text[i]);
        }
        return result.ToString();
    }

[jamietre]

By the way feel free to make pull requests if you find more things in the future that can be improved. This is a big codebase, some of which is well over a year old and hasn't been touched since CsQuery was little more than a proof of concept. It's impossible for me to keep everything clean by myself and I welcome the outside interest and involvement.

[jamietre]

Revised this to use StringBuilder native Append overload to add an char array substring directly

http://msdn.microsoft.com/en-us/library/ms149397.aspx