- What is your variable scope? Ie., in what parts of the program do you need it? - Is it a value type or a reference type. Reference types must always be "newed". Value types are more expensive to pass as parameters. - Does the type implement IDisposable? Then you should use it in a using { } clause. - Is the type immutable (like string or DateTime)? Then making changes to it is more expensive than you may think.
