What does the icon with a scale in the system tray mean?

[rogeriodec]

Normally, the icon that appears in the system tray shows the current CPU usage:



But sometimes this icon is momentarily changed to an image of a balance, with a red background:



What does this mean?

[edkiefer]

That means ProBalance kicked in reducing the priority of a process.

You can open the "Insights" tool and see what processes ProBalance acted on under the restraint count column.