XML Parsing far too slow. (How can I speed it up)

Question

Hey everyone,
I am converting a site from ASP to JSP and there are a bunch of pages that parse an XML document display certain information from it. One problem is that the JSP implementation I have is far too slow. It takes ~6 seconds to load the page as we wait for it to process. I am using <x:parse> and <x:forEach> to process it using an XPath statement with the appropriate predicate ($dom/foo/bar/Route[ID > 999] for example)
One problems I think is the size of the XML document. All the data for different pages is pushed to the same XML file and we use maybe 5-10% of the data in any one parse. I have looked at XML filters a little bit but can't seem to find a good example or a clear explanation as to whether or not this will even solve my problem.
The root node has 5 children and the biggest one which takes up probably 3/4 of the document isn't even used by us.
My boss wants it to be as fast as the ASP implementation which was really fast. It is 100% custom and manually probes the XML document and can skip any children which it knows won't contain any leaf's we want (mainly that big one) and is nearly instant.
Does anyone have any ideas?
Thanks,
John

Answer 1

Hey guys, thanks for the responses and sorry it took so long to get back - I have been busy with school an all.
Well, first off let me say that everything in general seems far slower than what I would expect. I have eliminated different parts and everything I do eliminate seems to make is significantly faster. Does JSP seems relatively slow to you guys? I am serving it from a slower machine too but it just seems quite a bit slower than I would have expected and I don't feel I'll ever be able to match the speed of the ASP implementation.
However, I think there is light at the end of the tunnel. I believe I found the slowest part. Surprisingly, it is not the importing or even the parsing of the file. They seem like they could take at the very most 1/2 second and the whole file takes ~5 seconds to run. The part that is causing the most delay is the five x:set tags.
<x:set var="attrID"  select="string($r/ID)"/>is one of them. If I replace them with a piece of servlet code to assign dummy values instead, it cuts the execution by 80-90%.
Any ideas why these may be so slow?
Also, do you think switching to a servlet implementation would be better? I actually use some servlet code that I mean to convert over to tags once I get it working. Shouldn't the tags be about the same speed and are considered the "better" way to do things if possible?
Thanks again,
John