Terrible lag when editing text in continuous view
For months, a good fraction of the time that I write large notes (via ctrl+t text) on a large score in continuous view (this is just the view that I use, not sure if this happens in other views), Musescore eats ~20% of my eight-core CPU and stops responding for seconds to minutes; after this time, some fraction of what I typed appears in the comment. The issue is especially bad when inserting newlines in comments but is certainly present even without that. I am currently working on a ~200-measure twelve-voice score, and it's especially bad.
Comments
The score in question is attached; I suggest going to continuous view, deleting all the text, and trying to insert some yourself, as the issues generally get less bad the less text there is. With that evidence in mind I imagine part of the issue is that whenever I add a character of text and especially a newline, Musescore recalculates the spacing between the lines (possibly worsened by text wrapping / page wrapping calculations?) and has to move the entire line down to "test" the options.
For the record:
When I open your score with version 3.7 on my really old (10 years!) Win7 computer (quad-core), there are absolutely no problems and no delay when adding staff text. And even there, the layout is rewritten with every new line.
Seems to be a MuS 4 problem an if other MuS 4 users confirm your problem, it should be reported on GitHub.