My computer is:
Ryzen 5 1600
16GB RAM
GTX 1060
With the texture at 2048x2048, using the smear brush as shown is incredibly laggy, it's actually unusable. Is this a common problem? Is there an option I can enable to make it work fast or am I just going to have to put up with it for the time being?
Smear is a noticeably slower tool for me too and I've got a PC with decently high-end specs. Personally I think the tool is pretty old and needs some developer love. But I'm glad you found the % control that helps.
PS: I just recommended you watch this course from your other question. I'm happy to see you've already done that :)