Experienced several system-wide freezes. Both are after not using Mac for a few hours.
Mouse can move, but clicking on anything just gives me a spinning wheel. And eventually system clock stops going.
What I notice before system freeze is: Spotlight is doing weird stuff in background hogging CPU all the time before dragging it to death. Or, photoagent process uses all CPU for no actual reason. Or, windowserver uses a hug amount of CPU but not all, then system becomes super slow.