Since converting to tubeless I feel there is more rolling resistance when on tarmac. I’m convinced the uphill tarmac climbs I use to link sections of trail together are tougher on the tubeless setup than previously with tubes. Am I going mad, is it all in my head? I’m running around 30psi in the tubeless setup.

Same tyres and pressure as before?

My experience, and the way I understand the physics, would be that for the same tyre at the same pressure, tubeless would offer less rolling resistance, as when the tyre deforms you are deforming less rubber (i.e. just the tyre and not an innertube as well). I definitely noticed less rolling resistance with my ghetto tubeless setups, not sure about proper UST with thicker sidewalls on the tyres…

Surprised at this if you’re running the same high pressure as before. Tubeless is all about reducting the pressure and riding smoother offroad. If you’d said you also reduced yer pressures from 30psi to 22F/25R then I’d have expected you to be a little slower on tarmac.
Perhaps the tube supports the tyre wall and stops any lateral flexing of the tyre?

Psychological? IME the decreased damping in tubeless tyres make them much noisier on hard surfaces.

The mad anal german magazine did a rolling resistance test on tubeless a few years back and found there was less. Go figure.