Hi there, here is a video demonstrating the issue.
In case it isn't clear, basically painting with the brush tool while the canvas is zoomed out, works fine. But when I zoom in very close, the brush begins lagging. No idea why. Just updated. All drivers updated.
Windows 10 64-bit
Intel Core i7-8700K 3.70 GHz
32 GB RAM
NVIDIA Geforce GTX 1060 6GB