I am surprised nobody has reported this already, especially given that it has been commented on the wiki page: https://wiki.jenkins-ci.org/display/JENKINS/Performance+Plugin?focusedCommentId=60918409#comment-60918409
The performance plugin currently captures JUNit failures, but not errors. That means a build will go green, even if there are errors - because the performance plugin does not capture these.
It should be quite easy to also capture errors in the tests, thus providing a complete solution for test reporting. I hope this can be prioritized and implemented quickly.