Windows 11: Excessive Background CPU Usage by System Processes

Before using repair commands, capture which process is actually consuming CPU; “system processes” is too broad to diagnose safely. In Task Manager, select Processes, click the CPU column to sort, and watch for several idle minutes. Record the process name, percentage, and whether usage is continuous or periodic. Do not end System, Service Host, or security processes. If the name is unclear, use Microsoft Process Explorer to view the process tree, owning account, and loaded DLLs. Then update Windows plus the PC maker’s chipset, storage, graphics, and network drivers, and run Windows Security’s Full scan after updating security intelligence. Perform the proposed clean boot afterward; if usage falls, re-enable services and startup items in groups until it returns. If CPU stays high even in a clean boot, share the exact process name and Event Viewer errors, because the next step depends on that evidence.