Freezing for a moment with certain actions

[MqcCheeze]

Issue type

Crash or freeze

Bug description

I have a large score around 800 measures at the moment which is expected to reach over 4000, by the end (yes its big, its around 1 hour 40m). Already around 800 measures certain actions like:

Selecting a half note and inputting it at the end of one measure to automatically carry over to the next, freezes Musescore for about 2 seconds. Control + Z to undo this also freezes.

However, if I were to put a quarter note at the end, then manually tie the notes together, this doesn't happen.

Anything that seems to involve multiple measures being modified at the same time will make Musescore hang for a second, this also affects changing key signatures.

I have tried this score in Musescore 3.x, it still freezes but for much less time.

Playback issues with large scores also, I would split the score into several smaller scores, then copy paste them all into one big score at the end but since Musescore still doesn't allow full copy pasting of all elements (see #15590 as it still hasn't been worked on or tagged since the assignee has not done any commitments since March 1st, please bump priority), I have to put up with the major lag.

Steps to reproduce

1. Create a large score with lots of measures.
2. Do any sort of cross measure notation

MuseScore Version

4.2

Operating system

Windows 11

[DaddyLudwig]

Other things I've noticed cause freezing and/or crashing in large scores in both MS4 and MS3:

• Lyric input, especially melismas(in which case, if it's mid-word with the hyphen key, I can mitigate it by going hyphen, random letter, backspace over and over, but if it's at the end of a word with the underscore key, I can't mitigate it, but it only happens with the initial pressing of underscore)
• Copying and pasting a doubled passage from one staff to another (for example, if I have a passage in the violas that is doubled by the cellos in octaves, sometimes it freezes during the paste step)

I generally expect there to be more lag as the file gets bigger so the lag, while it does slow me down, it isn't that big of a deal to me. What is a big deal to me is when that lag turns into a crash, that's incredibly frustrating and it's been happening multiple times a week, sometimes multiple times a day with my score of La finta semplice, a Mozart opera, which is around 1 MB in size.

[bkunda]

@DmitryArefiev pls investigate

[MqcCheeze]

@bkunda I'll keep editing this comment as I find more stuff it effects:

Additionally, it affects:

Changing voice number (e.g. voice 1 to voice 3 using control + alt + 3), however pressing undo, does not produce lag, only when changing it.

Changing time signature, action and undoing the action also create this lag.