MOHO 14 Freehand tool sluggish as strokes are added (when brush visualisation is active)

[Reindeer]

I prefer drawing than modelling, so I reeeeeally appreciate the MOHO 14 improvements on the Freehand tool. It's smooth and does very little to none of that annoying post-stroke adjustment it used to have. Many thanks to the team for this much needed step towards a more "manual" feeling MOHO!
That said, I'm experiencing the FH tool getting worse and worse as I draw. In other words, the more strokes I draw the more the Freehand loses its fluidity.
I noticed this drawing a cat. I filled the cat's fur with a good number of sketchy freehand lines, like I'd do with any drawing app (nothing too complex, just a handful of zig zag lines to film the area). When I started drawing another figure next to the cat, the fluidity and fidelity of the tool were gone. Curves became jagged, the line was sluggish and behaved as if I'd set it to have no point reduction. Not only, the pointer of the tool started to wobble, as if the software were striving to keep up with the vectors. I don't know if this is just on my computer or if others have experienced this.
Adding a new clean layer will make the brush work nicely again, but as I draw the Freehand tool will tend to slow down again.

I checked whether I had set the FH tool to have too many points but visualising the paths didn't really show that many.

EDIT: this happens only when the "brushes" visualising is on (bottom right on the timeline, next to layer fx).