Does adding a new flow (chock full of content) in some way impact the display speed or responsiveness when viewing or editing other flows?
Context: I’m using Dorico for a multi-movement orchestral piece and am deciding whether to break each movement into its own project. It would be nice to have everything in one place, but not worth it if the app will be perceptibly less responsive.
I currently work on project including 12 flows and I didn’t notice a slower response. i5 Processor with cheap graphic card and 4go ram
If you break it into flows, you can disable those that you are not currently working on. If it doesn’t speed up things, it makes not getting lost much easier 
There will be an impact on the speed if the flow is included in the layout that you are viewing, and also if it’s included in the default ‘full score’ layout. This is because by default scores contain all flows, one after the other. If you add a new flow then that gets added to the full score, and that has to be casted off, spaced, etc.
However, lots of people use the trick of creating a temporary layout containing only the flow they are currently working on (and maybe also with only a subset of instruments of interest) and then editing that, which can be a lot faster.
Thanks for the tip (Paul) and useful anecdotes (everyone else).
What I’m inferring is that any slowdown is a result of notes being rendered in the current layout, and that if data is out of sight (not included in the present layout) it doesn’t cause any slowdown. So by this logic, parts may be speedier than scores, etc.
There are a lot of factors that affect the performance of scores. In theory Dorico tries to minimise the amount of recalculation that’s required, so that if you’ve changed one note that may have changed the spacing within the bar then as long as it hasn’t caused the casting off to change (eg by pushing the last bar onto the next system) then it knows it doesn’t need to recalculate the subsequent changes. However there are still a lot of things that do have to happen which take longer as the score gets longer. That does tend to be a smaller percentage of the total redraw time though. So the best answer I can give is ‘it depends’…
But generally speaking, the less in a Layout, the faster the response tends to be? Just trying to adopt a practical strategy for the time being.
Yes, in general that principle holds, but you should also be aware that if you have had a full score layout open during an editing session, Dorico maintains that layout even when you’re not looking at it so that when you switch back to the full score, it’s quicker to switch back because the layout has been kept up-to-date with all of the edits made since you last looked at it.
If you work on e.g. a “focus layout” that contains just one flow, then a good way to make sure things are as fast as possible is to have only one tab open, and one window too, and make sure the single tab in the single window is showing the layout you’re interested in. Then save, close, and re-open the project: now only the layout that’s shown will be kept up-to-date by Dorico, and that may be faster.
You may also find that galley view is faster than page view, and that switching off View > Bar Numbers makes things a bit faster still.
The team has lots of potential strategies to continue to improve the responsiveness of the software as projects get larger, and indeed the 1.2.10 update includes a number of such improvements, so I hope in the future all of these kinds of mitigations will cease to be necessary.
Thanks Daniel! Exactly the sort of practical insider tips I was hoping for.
By “one tab open”, do you mean that only one tab should be available at the row at the top of the view?
I’m sure I’m mangling the terminology, but to put it a simpler way, should I click on the X on every tab except one? Or do you mean that there shouldn’t be multiple windows, each with a separate tab?
I mean both of those things: use one window, if possible, and in that window have only a single tab.