At least with the original Jolla phone the biggest constant nuisance in terms of responsiveness is the slight but ever-persistent lag when scrolling. Enough so that items within a list would show highlighted before scrolling. I believe this is actually an implementation error rather than the device itself as iPhones have always been good at scrolling.
That simple thing can make everything feel psychologically sluggish. I hope that is not the case with the 10ii but I suspect it will be.