cpu usagewindows
In Windows Task Manager and AVG Task Manager (included in TuneUp Utilities), I see that the sum of all the running processes is much lower than the total CPU usage shown in "performance" tab. Does this mean that my PC is running a hidden process or some malware that's not displaying in the Task Manager?
EDIT: inbuilt monitor showing this too, and show processes from all users showing too. laptop is two-cores, and I'm taking total load of both.
Process Explorer is a much better tool for inspecting processes than the built-in Task Manager. While it might not answer your question completely, it may give you more insight into the problem.
I looked at the picture again and see that the sdclt.exe is highlighted in green. This means the process is started. I look at many xperf traces which also show this symptoms.
The solution to reduce the CPU usage is to stop the ConfigNotification task in the Windows Task Scheduler:
Task Scheduler - Microsoft - Windows - WindowsBackup
Please, also contact Microsoft support and open a support case. They need a case to produce a fix for the backup task.
Best Answer
This is because the task manager round up or round down the CPU usage values per process. You can see a lot of process using "0" CPU time, this is false, they use "0,xxxxxxx" cpu time.
What you need is a process manager showing more precise value to you.
Some process can also be hidden (negative PID, running as another user) or some piece of hardware may have direct access to the CPU by passing your operating system (but probably not)