maximum size for xml files

Question

whats your rule of thumb for maximum size for xml files.

What if I ask maximum no of records, and one record have 10 values for instance? Another condition is we are

Answer 1

My rule is that if it's too slow to do what I want, then it's too big, and your data probably needs to be moved to some other format... database or such.

Traversing XML nodes or using XPath can be a dog.