Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: Radeon Pro 580 ATI Technologies Inc. 4.5.13537 Core Profile Context 24.20.13001.1010
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Short description of error
(idk if this is a bug or just how it works)
The display is 5k. I'm sculpting on a default Suzanne head. Sculpting is very slow. The cursor lags behind. Everything else including navigation is fine. Sculpting performance improves as I scale the Blender window OR viewport down. at 1/4th the screen (Windows 10, Blender window docked to one corner of screen), I'm able to sculpt on a Suzanne head that's been subdivided to 8 million faces. Everything is very responsive. And yes, with window maximized, it's slow even when it's not subdivided at all).
Exact steps for others to reproduce the error
Maximize the Blender window. Add a Suzanne head. Subdivide it upto 8 million or don't. Sculpt.