I have been working on a orchestral score. I have had several flows as experiments I tried the condensing score for fun, but turned that off. I had several custom scores for WW, brass, strings, etc. Eventually the Dorico file got so big and slow that it became impossible to use. It takes over 3 minutes to load on a pretty fast Windows computer. Worse, just about anything you try to do puts you into a 3 minute delay.
I followed the advice on several of these threads and none of that worked. I applied the “silent” template, but the file remained huge (about 26 MB). I eventually decided to create a new score from scratch. It literally took me 3 hours to cut and past the music to the new template. I did it one section at a time (woodwinds, then brass etc), then removed the players and layouts from the problem file and saved both files. Each of those cycles took about 30 minutes because it involved a half dozen coffee breaks for the 5-minute delay.
In the end, I think my new template file is OK and not causing a performance problem yet. But I eventually deleted all flows and all but one of the players from the problem file, leaving a single measure with no notes. And it is STILL almost 26MB. And it still takes 5 minutes to load. When I examine the Dorico file, I find supplementary_data\vstaudioengine\ accounts for almost all of the file size, even though I have no VSTs in the project at all (and no notes).
I bet many of the problems people have reported on large scores are some variation of my problem. I hope somebody will take a hard look at this file. If you can solve this, you probably will eliminate most of the large-score performance complaints.
The Dorico file is here: https://drive.google.com/open?id=1XiEA8qpiWyEJf82Wd8OsJqSVSmqqJGnY