I'm doing some performance testing of DITA processing on a large document (1500 topics) using the XHTML transform (which means that all the relevant data processing is in XSLT, not some other processor).

When I run through Oxygen 15.2, which means I'm using Saxon EE, the process takes about 6 minutes to run. 

When I run on the command line, which means I'm using Saxon HE, the process takes about 12 minutes.

Is my analysis that Saxon EE is twice as fast as HE correct or should I look for some other explanation for the performance difference?