When I saw Altova's latest newsletter I had a good chuckle. I deal with very large XML datasets, between 100MB to 1GB. I use a variety of XSL transformation engines: Altova, MSXML, Saxon, and Xalan. Each has their strengths and weaknesses. None of them handle the processing of large XML datasets well. What I found extremely funny about Altova's claim was my personal experience in running large XML datasets, on a regular basis, through the various XSL transformation engines. Most of the XSL transforms I run take hours to complete. Xalan by far is the slowest, but it handles large XML datasets as well as Saxon does. MSXML v6 is faster than Xalan and Altova has similar completion times as MSXML. Both Xalan and Saxon handle larger XML datasets, approximately 50MB more of data, than either MSXML or Altova. Saxon by far has the fastest completion times. Many times Saxon completes the same XSL transform a full 30 to 40 minutes before any other XSL transformation engine. From my perspective, while running conformance tests is nice, in my "real" world scenarios, what I see is that Saxon appears to make more efficient use of memory and runs my XSL transforms much quicker than Altova does. I really had to chuckle at their claims. As you indicated, any vendor can game performance testing since they know their products strengths. Keep up the good work on Saxon, Andy.