SaxonJS performance conserns

I just found and started using Saxon-JS to be able to run Schematron validations on Peppol (Peppol.eu) messages and it works great!

I've "pre-compiled" the Schemat's needed into JSON (using schxslt and xslt3) and I am then executing the SaxonJS.transform() on the data.

As these stylesheets are fairly big it takes some time and performance is of key as it is run through a API.

I run the three calls in a Promise.all() and have added timers. From the timers I can see that the function calls happens in parallel but the execution of SaxonJS.transform() seems to be sequential, i.e. when the first SaxonJS.transform() returns the next starts...

I tried adding threads to the code to get it running in "workers" but I need to send a XMLDom object to the function and threadsisn't supporting that it seems...

There's about 430ms in between the two executions of the runTransform() and they are called like:

let [xsdResult, valid, valid2] = await Promise.all([
  xsdValidation(event, xmlDoc),
  runTransform('EN16931-UBL-validation-preprocessed.sef.json', event, ves),
  runTransform('PEPPOL-EN16931-UBL.sef.json', event, ves)
]);

Shouldn't the functions run in parallel (at least "more" in parallel)?

It was another await in function runTransform() that was "blocking" and not the SaxonJS.transform() as initially thought...

Mind those Promises... :o