Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: Radeon RX 560 Series ATI Technologies Inc. 4.5.13558 Core Profile Context 26.20.11015.5009
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Short description of error
Smooth brush freezes on highpoly mesh
Exact steps for others to reproduce the error
Smooth brush freezes in sculpting mode when working with models from 4...8 million triangles. The lag happens at the beginning of the use of the brush for a few seconds, then the brush is working fine. In the version 2.79 brush works fine with any number of polygons.
Addition: In version 2.79, this problem is also there, but only when you first use the brush, all subsequent times there is no freezing. Probably, the more powerful the computer, the more polygons it takes for this problem to make itself felt.
[Based on the default startup or an attached .blend file (as simple as possible)]