Cavitation is usually referred to in a hydraulic system when the flow demand of the pump is too high, or there is some sort of blockage in a line, causing the line to crush in on itself. Kind of like pulling a vacuum on a system not designed for a vacuum.
I believe what racer is referring to is sucking air through the threaded fittings causing air bubbles to run through the pump and essentially causing a “misfire” on a plunger. You will feel it as a studder from your pump.
If you do use threaded fittings it is essential to ensure no leaks. I agree that it is easier to develop leaks using threaded fittings. I put mine together this way because I honestly wasn’t sure how it well it would work.