Bug 465397

SUMMARY
Since the last couple of days, 5.27 branch produces a pretty hefty memory leak for me in the X11 session (Wayland is unaffected by this). The symptom is an ever increasing memory consumption for the plasmashell process, as well as increasing lag on the desktop: Drawing a selection rectangle on the desktop starts to become choppy, as well as opening a context menu and hovering over its entries.

I'm not sure exactly which commit caused it, and I don't know when exactly it began since I've mainly been testing the Wayland session, but I'd say it started at least 4 days ago (but well after beta testing for 5.27 began).

My plasmashell consists of the following:
Desktop:
- digital clock
- system monitor: network (line chart)
- system monitor: CPU (1 line chart per thread, 32 charts total)
Panel (top):
- standard kickoff
- weather
- CPU usage (%)
- GPU usage (%)
- RAM usage (GB)
- download (text)
- upload (Text)
- crypto currency price x2 (non-builtin plasmoid)
- window title
- global menu
- system tray
- digital clock
- peek at desktop

I can provide my plasma-org.kde.plasma.desktop-appletsrc if you think it helps, but there are a lot of access / session tokens I'd need to purge first.


STEPS TO REPRODUCE
1. Log in to an X11 session
2. Open your resource monitor of choice and observe the plasmashell process
3. Wait ~10 minutes

OBSERVED RESULT
plasmashell's memory usage slowly creeps up, desktop becomes stuttery (after ~10 minutes, memory usage is already at ~1 GB for me)

EXPECTED RESULT
plasmashell's memory usage remains constant, desktop remains smooth

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo
(available in About System)
KDE Plasma Version: 5.27 beta
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION
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