OK I downloaded your file and ran it in Photo 1.7.1 using a Intuos Pro Medium (driver 6.3.35-2) in bluetooth mode. Painting with brush is fluid. Max CPU usage Photo reaches is around 63% if I scribble really quick and messy. Will download 1.7.2 soon and test. I'm 2017 rMBP running Mojave. Default res. Photo HW acceleration on. Cheers.