RE: Question about XSLTC
> There have been scenarios where increase of speed was more > then 20 fold (!). Actually I had one client who asked me to visit to look at performance problems with a stylesheet running under Saxon 6.5. I spent half an hour looking over the code, couldn't see any obvious reason why it should take 40 seconds to run, so I suggested that we try it under Saxon 8.x, and it ran in under a second. They paid me, I took the next train home, and I never did get to find out exactly why it made such a difference. That's without any code changes to take advantage of the new features in 2.0.... To be fair though you can't always expect this. Sometimes you just strike lucky when you switch from one processor to another because the optimizer happens to recognize a particular coding pattern that you've used. Such effects don't tend to be repeatable from one stylesheet to another - but the more mature the processor, the better your chances. In comparison with rewrite optimization, byte-code generation at the back end (as done in XSLTC and in the latest Saxon-SA) only makes modest contributions to overall performance - a factor of two is probably all you can hope for in most cases, less if your stylesheet is dominated by parsing, tree-building, serialization, or sorting costs. And one of the downsides of doing byte-code generation is that once you've done it, the development cost of introducing new rewrites is greater because they often have to be supported in the code generator. Michael Kay http://www.saxonica.com/
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