I am not Microsoft’s biggest fan, since I was a Macintosh fanatic in the old days, but had to convert into the Wintel platform for about 10 years ago. But I have to admit though, when comparing Microsoft’s XML parser with the ones that are built into Notes/Domino, that their products sometimes are great!
When comparing Microsoft’s XML parser with the other two, I created an agent that parsed a big (over 700 KB) and complex XML document and read an element’s value. I did this 25 times per parser, and came up with this interesting result (average execution time per parser) when executed in the Notes client:

1. Microsoft XML Parser: 0.2 seconds
2. NotesSAXParser: 2.2 seconds
3. NotesDOMParser: 2.5 seconds

When executed on a Domino server, the result was a bit different, since the server is a bit old:

1. Microsoft XML Parser: 1.0 seconds
2. NotesSAXParser: 5.0 seconds
3. NotesDOMParser: 7.7 seconds