The size of XML elements actually does directly affect performance times. The more text you have to parse, the longer it will take. Rob I hope you didn't misunderstand some of my earlier points on this though. I don't mean in any way to give the impression that tag size is the biggest factor in terms of file format performance because it's not. There are a number of other architectural issues that play a much bigger role. That said, the size of the tags does have an impact .