I have setup a job with that runs a suite with 700 tests. The suite produces about 300 kb of output on the console and a JUnit XML file that is about 500 KB. If I access /testReport/api/xml for a build a huge document is returned since stdout is repeated for every single test case although JUnit only stores it on a per suite basis.

That means Hudson explodes a 500 KB of JUnit log files to around 210 MB!

Here is an example:

JUnit XML input: http://mylyn.eclipse.org/hudson/job/mylyn-test-standalone/71/artifact/build-results/test-results/TEST-org.eclipse.mylyn.tests.AllHeadlessStandaloneTests-3.5.xml
Hudson API output: http://mylyn.eclipse.org/hudson/job/mylyn-test-standalone/71/testReport/api/xml