Hidden staves slows down user interface as much as visible
I have a sheet with 18 staves, 107 measures each, totalling 1926 measures. Working with such a big sheet is naturally slow because of relayouting. However, when hiding staves by unchecking Visible in Add->Instruments dialog, you should be able to gain speed boosting. That seems, however, not to be the case. If I hide all staves but one, it still takes about one second moving one singel note half a step up or down. Equally long time as when all staves are visible.
GIT commit: 3543170