Use "as" operator (USEAS)

Description:

C# allows you to replace the type check (is) and type cast operators with the single as operator. This makes the code clearer and improves performance.

Incorrect:

if (obj is string) { 
    string str = (string)obj;
    return str.Length;
}

Correct:

string str = obj as string;
if (str != null) { 
    return str.Length;
}