If the XML is basically a repeating structure, you will find splitting it into smaller chunks is more manageable that handling one massive file.
Heh! All I have is the very large file. I've no control over that. I'd have to open it to split it up - and that's what I can't (easily) do.
Equally, if you want run XPaths against it then you should really be using an XML database (such as eXist), or investigate streaming options.
As I've mentioned, I'll check this out. Guys, I don't want to make a big thing of this. The world won't end because of it. I was only enquiring, originally, just to find out whether what I was experiencing was expected or whether I was doing something wrong. Being new to this sort of thing, I wasn't sure. I'm grateful for all your input. Thanks Peter