In version 22.0[.0] the problem with lagging curves seems to be resolved, at last.
But I don't find it mentioned at the page Fixed issues in Photoshop:
https://helpx.adobe.com/photoshop/kb/fixed-issues.html#photoshop-desktop-fixed-issues
Closest: "Hue/Saturation not updating real-time".
(i7-9700K 3.6 GHz, 64 GB RAM 3200 MHz, GeForce GTX 1660 Super 6GB, Samsung 970 EVO Plus 500 GB M.2, Windows 10 Home)
2.11.0.0