Brush tool preview

When using the standard brush tool on my Mac I can paint with the brush and the preview looks pretty much like the final result so it feels fairly like using ink. On my Wacom Mobile Studio (Windows 10) the brush preview is kind of faded as you draw and has lines through it. A bit like a ghost image before I release and it renders.

Why is this? I much prefer the feel of the Mac version as the other is a bit hard to see clearly. Could it be the processor in my Wacom is an i5 whilst my mac has an i7? Or is this a Mac vs Windows thing?

Also I'm using slightly different versions (Mac 19.1) and Wacom 19.2.1

To be clear, I'm talking about the standard old school brush (B) - not the newer paint brush tool (Y)

Thanks.