Developing a series of POCOs on my project, and just realized that some of them doesn't need the using System; clause.
Is there any performance or size penalty for leaving unused using <module>; on my objects or project ?
Will my classes get bigger, or slower, or bloated because of this or the compiler/optimizer is smart enough to take care of this?
no there are not performance issue .
it is just a readability matter(I would suggest to remove them)
more info at: Why should you remove unnecessary C# using directives?