UI Memory leak

[metasekk]

Issue type

Crash or freeze

Bug description

Almost all interactions with the UI increase the memory (RAM amount) indefinitely, slowing down the interface progressively. Things have seriously worsened in master 4.4 (Qt6), but the issue occurs in previous versions too.

Steps to reproduce

Main ways identified to increase the memory (in decreasing order of importance):

• Open windows (e.g. +50 Mb for "Preferences" each time)

=> Greatly improved in #23495 (+2 Mb for each opening/closing cycle instead of +50 Mb).

• Open menus (+20 Mb each time; +1 Mb when closing)

=> Greatly improved in #23495 (+0.25 Mb for each opening/closing cycle instead of +20 Mb).

Issues below are still reproducible:

• Click/Hover quickly over submenus (+10 Mb, e.g. "File > Open recent")
• Move/drag the score (between +1 Mb/s and +10 Mb/s, depending on the movement, and the duration when dragging)
• Zoom in/Zoom out (~1 Mb for each)
• Selecting two bars alternately in a score, or selecting one then releasing it by clicking elsewhere (~300 kb each time)
• Open/close palettes (+10 kb each)

Note that it only occurs when a score is open.

Screenshots/Screen recordings

https://drive.google.com/file/d/1FRGApBrWmJTWLxiq2I-89gA6ICNtWtcY/view?usp=sharing

MuseScore Version

Tested on 4.4, 4.3.1, 4.2.1 and 4.1.0 (much slower growth in 4.1.0 and 4.2.1, but still present)

Regression

I don't know

Operating system

Win10 (22H2); RAM: 16Go; CPU: Intel Core i5-9300H (2.40GHz)

Additional context

Alongside other identified leaks (e.g. #23112 and #22721), it might partially explain #22094 and #20889.
Reported on musescore.org multiple times (e.g. https://musescore.org/en/node/364227, https://musescore.org/en/node/353935...)

Point 2 ("Open menus") item is a duplicate of #22885.

[zacjansheski]

Closing as fixed by #23495

Thank you!