"Tastes great, but very filling." That's what some developers say about XML and CMS. XML's portability is great, but the XSLT part can be quite slooooooow, and if your dynamic content compels you to do transformations at runtime, your users often suffer -- regardless of what your vendor tells you about caching. Perhaps some hope, then, resides in the coming of XML appliances. One vendor, DataPower sells an XSLT accelerator that sits in front of your web farm and supposedly speeds performance as much as 20X. We haven't tried it, and at $US 50k per unit, it's not for everyone. But like other network plug ins, XSLT accelerators will probably become a commodity -- one more step towards bringing XML to the CMS masses...
Check out DataPower