The call to reset before each test can take around 30ms (for the validation plugin testsuite, probably more for bigger test fixtures). The current code uses this:

$("#main").html( config.fixture );

Using only DOM methods, it can be considerably faster:

document.getElementById("main").innerHTML = config.fixture;

This causes a few dozen tests in the jQuery core testsuite to fail. Need to figure out why they are failing.

Also there are probably other areas for performance tuning. Needs some careful measuring.