Muffin compositor leaks memory at ~100-140KB/s on X11 with dual monitors

Environment

• Cinnamon 6.6.7, Muffin 6.6.3 (Linux Mint Zena / Ubuntu Noble base)
• NVIDIA GeForce RTX 3080 Ti, driver 590.48.01 (proprietary kernel modules)
• X11 session
• Dual ultrawide monitors: 3840x1600@144Hz (DP-4) + 3840x1600@60Hz (DP-2)
• No custom applets, extensions, or desklets installed

Bug

The Cinnamon/Muffin compositor leaks memory continuously during normal desktop use. After ~10 days of uptime, Cinnamon's RSS reaches ~930MB (starting from ~200-300MB after a fresh login). The leak rate measured via ps -o rss sampling is approximately 100-140KB/sec, monotonically increasing:

Timestamp   RSS (KB)
1772590230  929280
1772590231  929304
1772590232  929592
1772590233  929596
1772590234  929884
1772590235  929892
1772590236  930180
1772590237  930372
1772590238  930432
1772590239  930432

Impact

Desktop experience degrades over time, requiring a reboot.

Workaround

Logout/login resolves it.

Notes

• No STACK_OP_ADD errors or other Muffin warnings in .xsession-errors correlate with the leak (only a brief burst of 14 during a Zoom tray icon removal).
• GPU is at P8/idle clocks during desktop use — the leak appears to be on the CPU/system memory side, not VRAM (stable at ~1450MB for Xorg).

Begin with Muffin's X11 compositor path and monitor Cinnamon's RSS using ps -o rss; the report provides no source file or test entry point. Reproduce the leak with the listed dual-monitor setup, isolate the retaining path, and verify that RSS remains stable during extended desktop use.