I have just tested it myself (Windows Ink on and off). Maybe there are differences in hardware, brushes used or canvas settings (I tried both simple screen resolution file and (my usual) B1-300dpi-RGB/16bits) but both options are lagging here in different moments. Windows-Ink-on usually at the begging of the stroke (and when grabbing a colour change slider, for example) while Windows-Ink-off lagging during drawing a longer stroke, curve. I have to admit, that W-Ink is not lagging permanently, sometimes it is pretty responsive. But having it enabled in Windows is a pain to use anything else beside Affinity. System with W-Ink enabled treats Wacom pen as "touch" and it is burdensome! Also problematic shortcuts, highlighting text not working and so on...
Dear Serif, is there a way to have some kind of best-of-both-worlds solution (fast, responsive, precise graphic tablet interface without W-Ink load)? Or at least an option to choose a lesser evil?