Photoshop loads one core?

Question

Adobe Photoshop

I ran into a performance problem in Photoshop, the machine is not the worst one like (8700k, rx588, 16-3000mhz, ssd)
One of the latest version 21.1.1. Even ordinary brushes podlagivayut when drawing, when you run through the tools with an arrow, dullness is noticeable. In the selection and mask, when you play with the sliders, everything is completely bad there - 1 + sec delay.
I don't know where to dig. I would probably use it that way, thinking that such a feature of the program .. but I remember exactly two years ago, on an old machine, I definitely didn’t have such problems. In the performance settings, I already tried to set the parameters in different ways. In Google, it’s somehow not particularly about this, in the guides of the adop it’s banal. I noticed when you move the slider in masks at this moment, the 12th core is loaded at 100% and the rest are chilling, shouldn't it be?