What kind of volume do you have? If you have tens of thousands of invoices every month and they all have tons of lines, etc, I can see those processes being slow.
If it's taking multiple hours and your volume is pretty limited, I'd probably complain to NS.
It's admittedly been a loooooong time since I've dealt with ARM and when I did so, the volume I was working with was very small, but I don't ever remember it taking an excessive amount of time.
Though tbh, it seems like the performance of literally everything in the system seems to get worse every release.