Done a fair few prints with 4.0 now and while I can't honestly say there's any quality or speed difference over 3.1 - there are a couple of annoying changes.
The only difference I've noticed is that the speed settings now have their own tab.
When printing via usb, 3.1 would show me a 'live' animation in real time of the print in progress.
4,0 does not. Just shows the static printhead and occasionally updates the model - but I no longer get a live animation of what's being printed.
Also if you use the 'play/pause' animation controls at the bottom of the screen for a virtual print preview - again I no longer get an active animation of printhead movement. On the slowest settings I now just get a pretty fast layer by layer animation, and on the faster settings it just builds it - again layer by layer at a ridiculous speed.
Is there some method of changing this back to how it was in 3.1 ?
It's actually really useful to be able to see the toolhead movements - in real time - rather than just a whole layer in one go.