XML SAX parsing performance measured using the XMLTest performance benchmark shows large variablity in measured throughput from run to run. Details of the test setup -

Test: XMLTest
SAX Parser: Xerces bundled with JWSDP1.3
Document size: 905KB
Number of threads: 4
JDK version: build 1.5.0-beta2-b46
JVM options: -server -XX:CompileThreshold=100 -Xms256M -Xmx256M -XX:+AggressiveHeap

Solaris test machine: V880, 4 X 1200 MHz, 16GB
Windows 2003 test machine: 8 hyper thread CPUs, 2.78 GHz Xeon, 4GB

The different throughputs (transactions per second) obtained for 10 different runs for Solaris 9 and Windows 2003 are given below.

Solaris 9: 43.733334 44.033333 44.633335 43.966667 40.0 45.233334 46.066666 42.7 37.033 43.966667
Windows 2003: 59.133335 61.1 58.066666 49.1 65.6 53.2 60.166668 59.266666 52.266666 67.9

For Solaris, the range is about 25% of the minimum value and for Windows the range is about 40% of the minimum.

Since XMLTest is a simple XML parsing benchmark, the measured throughputs for different runs should be within 1-2% of each other.