Memory leaks in macOS 12 are apparently triggered by a customized mouse pointer. If the “normal” pointer size is not used for the cursor or if a different pointer fill color or pointer edge color than the standard black and white is used, this can lead to excessive memory usage in various programs.
Bugfix expected from Apple
According to user reports, individual apps such as the Firefox browser sometimes suddenly claimed working memory in the double-digit GByte range and were able to slow down the entire operating system over time – up to and including a warning message.
The current Firefox version 94 is already counteracting this and is intended to reduce memory leaks, it says in Mozilla’s bug tracking tool Bugzilla – the problem could still occur. The bug has been reported to Apple and is expected to be rectified in a future macOS update.
Workaround: reset mouse pointer
As a workaround, Bugzilla recommends switching off adjustments to the mouse pointer and returning to the default pointer. This is possible in the system settings under “Accessibility” for “Display”. In the “Pointer” tab, the pointer size should be set back from an enlarged form to “Normal”. Any adjustments to the pointer edge color and pointer fill color can also be reset there. However, this workaround may not be an option for users with impaired vision.
The modification of the pointer color is a novelty of macOS 12 Monterey, which many users have tried – and thus possibly ran directly into problems with memory leaks. After resetting your cursor adjustments, your Mac should restart.
It remains to be seen whether a customized mouse pointer is the only cause of memory leaks in macOS Monterey. According to individual reports, excessive RAM usage by individual apps can occur even with the cursor unmodified. In this case, all that remains is to wait for a bug fix from Apple, the manufacturer is currently testing macOS 12.1.