Sure. There's an optimal tire pressure for each tire, and the wider the tire, the lower the pressure. The point I was making was that a wide tire at optimal (low) pressure is not significantly slower than a narrow tire at optimal (high) pressure. However, any particular tire can be underinflated relative to its optimum, and become sluggish.

On my mountain bike it's very noticeable when I'm below 30 psi on a road, but the difference between 30 and 50 is not noticeable in terms of speed (hard cornering does feel a bit different).

I do, the difference is "woah this thing powers itself" kind of noticeable. Sure I could get the same average speed on my ride, but at the cost of so much more effort on low pressure tires.

Bicycle Quarterly put forward the idea that higher presure tyres feel faster because they transmit more vibration. Normally we would feel that vibration increasing as we go faster.

However,even though they feel faster, they’re actually slower. That extra vibration is coming from vertical deflection that a more supple (lower presure) tyre would allow to stay as forward momentum.

Personally I keep “25mm” (GP4Ks always seem to measure closer to 27mm for me) somewhere between 70-80 psi but then I’m the sort of madman that thinks I can feel the difference with latex inner tubes.