Yeah I usually try all those things before posting here. I have reset photoshop preferences. The problem is that the lag is greater than in previous versions with the same settings. In super small images with no layers, the lag is smaller but I always work with large DSLR images and I work with 20-50 adjustment layers on a regular basis (been doing so for the past 15 years professionally) and never had this problem.
Add that to the fact that "show overlay" doesn't work in the liquify filter and that adjustment layer changes aren't smooth and instant like many versions ago, so it makes me suspect there's still some rendering bug that needs addressing.
Thanks