The solution is.....

Window NT doing strange things! When I wrote the script originally I ran it at home, however at work where I started to test it this morning, we have a Filewall and MS Proxy...

Even though the MS winsock proxy is supposed to deal with things transparently, it clearly doesn't work for processes running under CGI, probably a user/permission problem. Anyway when I run it under CGI Matt's LibXML waits around trying to access the external DTD, which it can't, so it gives up eventually - hence the minutes of waiting. If you remove the DTD then it runs just as fast as it does on the command line.

I now have to remove the DTD from the input XML files or make Matt's LibXML parser ignore the DTD (which is what I thought $xml_parser->load_ext_dtd(0); did), but I was wrong.

Many thanks to kappa, though it was the wrong suggestion, it did made me think external, and hence track down the answer!

I should have know that if it runs okay from the command line, but not CGI it almost certainly is a permissions problem....!

As ever thanks in advance......!