Some hopefully relevant notes from my experience of this sort of thing in answers here and here.
There's no reason your existing CppUnit setup combined with something like the scoped_timer (see second of the above) and a bit of postprocessing to some charts maybe shouldn't satisfy your needs. While I believe CppUnit includes a plugin ("Clocker" ?) which will log out unittest times, I don't think it's actually that useful for this sort of performance testing in practice because you invariably end up wanting to time just part of each test and not all the setup code.
