Xslt is oftentimes thought as a tool to take input xml, and run transformation to get html or some xml on output. Our use case is more complex, and is closer to a data mining of big data in batch. Our transformation pipelines often take hour or more to run even with SSD disks and with CPU cores fully loaded with work.

So, we're looking for performance opportunities, and xml vs json might be promising.

Here are our hypotheses:

• json is lighter than xml to serialize and deserialize;
• json stored as map(*), array(*) and other items() are ligher than node() at runtime, in particular subtree copy is zero cost in json;
• templates with match patterns are efficiently can be implemented with maps();
• there is incremental way forward from use of xml to use of json.

If it pays off we might be switching xml format to json all over, even though it is a development effort.

But to proceed we need to commit an experiment to measure processing speed of xml vs json in xslt.

Now our task is to find an isolated small representative sample to prove or reject our hypotheses.

Better to start off with some existing transformation, and change it from use of xml to json.

The question is whether there is such a candidate.