PSC's are by no means performance sleds, but that is not what the boats are about, as adressed well in the quote above.
Part of the problem is, that most cruisers boats are loaded down with more supplies than is needed for the cruise, 3 anchors with 250 ft chain each, a 100 # dinghy with an engine that needs a crane, four 5 gal cans on the rail, liferaft, diving equip, spares, full tanks, etc. etc.. Scrutinizing every pound onboard is even more important for sailors with heavy displacement vessels, if you want to keep it moving in the light stuff.
With good sails including an asym, strict weight management and a little skill a PSC should keep up with boats of similar LWL above 5 kn TWS.
We sail a PSC 31, and after putting her through a serious diet last year, the waterline dropped by 2" with the boat fully loaded for the winter cruise. And the low to moderate wind performance improved noticably.
A good set of binoculars will also help your perception of your speed as compared to the boat passing you. You will be able to see the steady stream of water from the transom, and immediately feel better.