I am sorry for this rudimentary question.  I am not a novice user, but have been using Windows for over two decades. 

I used to think Windows Explorer was File Explorer, but sometimes it still has very high CPU usage after all File Explorer windows are closed.  Searching Windows Explorer on the machine turns out nothing named Windows Explorer.

Hi,

File Explorer , previously known as Windows Explorer, is a file manager application. You can find it in Windows Explorer, process name is explorer.exe. For the high CPU issue, what is the detailed information in task manager? We can also use WPT to capture the detailed the CPU information, please see the guide in the link below, then upload the collected trace here for further analysis.

http://blogs.technet.com/b/yongrhee/archive/2012/11/23/wpr-xperf-capture-high-cpu-disk-i-o-file-registry-networking-private-bytes-virtual-bytes-paged-pool-nonpaged-pool-and-or-application-slowness.aspx 

Thank you for the response, Yolanda.

I will capture it when it happens again. I am sure it will because it has been happening frequently.

Hi Hong,

Thanks for your feedback, if issue happens again, please feel free upload the captured trace file here.

It's always recommended to run virus scan to eliminate malware\virus to ensure the security.

Regards

Hi Yolanda,

What a good timing!  I was recording a performance file. It is happening right now.  I have closed all File Explorer windows and the Windows Explorer CPU usage is about 50% on an Intel quad-core machine.  I took a look at the etl file, but could not find any clue.   Here is the file.  Any tip will be greatly appreciated.

Hi,

This the analysis of the etl file:

It clearly shows that explorer.exe takes up almost 50% cpu, and the culprit of the high CPU is two threads under the process: TID 4852 (24%)and TID 9184(24%) (the number of TID can be different each time you capture the trace), to further find out what the TID refers to, you can use process explorer to find process running under explorer.exe, find the culprit

http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

Or use Process monitor, filter the two TIDs (it depends on the real-time capture result), then see what the two TIDs refer to.

Add:

There's another tool named shellExView which can list shell extensions within Windows Explorer, you can refer to the guide below to disable third party extensions, test the result

http://www.nirsoft.net/utils/shexview.html

NOTE: Please Note: The third-party product discussed here is manufactured by a company that is

independent of Microsoft. We make no warranty, implied or otherwise, regarding this product's

performance or reliability.

Thanks a lot for the very helpful elucidation, Yolanda.  I will follow your instructions next time when it happens again, and report back here.

Hi Yolanda,

Thanks again for all the tips.  I closed everything that I can when this happens, the explorer still consumes a quarter of the CPU on a quad-core machine. Its PID is 3000 and I have no idea what it is doing.  Any hint would be greatly appreciated.

Hi Hong,

Though ExpressTray.exe is not taking up too much CPU, I still recommend you end the process to check the result since it is the only process we can see under Explorer.exe.

Disabling third-party shell extensions with shellExView tool can also help us to fix explorer.exe associated issue.

And from the snapshot you pasted above, it still shows a lot of applications running background, I recommend you launch task manager, then end all the processes to eliminate any unexpected  factors.

I deleted all thread under explorer.ext except procexp.exe that I was using to investigate and snagit32.exe used to take the following screenshot.  explorer.exe was still taking 50% CPU.  I will start deleting other processes next time per your suggestion.

Hi,

It's recommended to find the associated TID in Process Montior If issue persists as I mentioned in my first reply

http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx

Meanwhile, we can also boot into cleanboot mode to check whether a third party program is the culprit, you can refer to the detailed guide in the link below

http://support.microsoft.com/kb/929135 

very high CPU usage after all File Explorer windows are closed.

So, what is showing on the screen then?  explorer.exe is your Desktop, Taskbar and Start Screen so what are they doing?  If necessary you could try restarting explorer.exe via Task Manager (right-click, Restart on Windows Explorer).

Sorry, Robert, but I have somehow missed the notification about your reply.  According to Yolanda, Windows Explorer is File Explorer.  I always close all Windows of File Explorer when this happens, and it rarely helps.  Task Manager often shows Windows Explorer using more than 50% of CPU on a quad-core machine.

I finally found a culprit today, so I wanted to report back and saw your reply.  The culprit is Snagit Editor (32 bit). When the high CPU usage by Windows Explorer happened, The Task Manager shows Snagit Edit was using only about 2% of CPU. It was a background process because I closed everything I could to diagnose this.  As soon I killed the background process Snagit Editor, the Windows Explorer disappeared from the Apps list, and the CPU usage dropped sharply.  This happened twice. 

It is strange that Snagit Editor has never been shown under Windows Explorer either in Task Manager or Process Explorer. I have tried to kill every process under Windows Explorer and it never solved the problem.