What is the computer "doing" when it is running slow and task manager is not showing any CPU activity?

Typical example is when shutting down a memoryintensive application. It can take quite a while before the computer gets back up to speed. Is there some inherent cost in releasing memory? Or is it throttled by some kind of harddrive activity, and if so is there any good way to track that?

I usually bring up task manager when a computer is running slow, and usually sorting by cpu activity can show what process is causing the problem, but sometimes there is no activity showing. And yes I "show processes from all users", I have been wondering this since the days win2k :)

Joakim Tall

Posted 2013-10-23T14:24:32.247

Reputation: 13

Hardware issue is a possibility. HDD issue is likely. Memory issue is also likely but more often causing a BSOD rather than just a froze, and keep going. – Darius – 2013-10-23T14:29:30.437

5It's probably all the memory book-keeping. Pages have to be deallocated from both the page table and page file, on top of any files that have to be saved to disk. What does disk activity look like while the application is closing? Does the HDD hit 100% utilization? – Darth Android – 2013-10-23T14:31:29.407

The point of the question was to be rather broad, and it was excellently answered below, so I would not call it too broad! – Joakim Tall – 2013-10-24T15:00:07.973

@DarthAndroid I'm not that familiar with the page terms but I guess thats basically the same advice as in the answer below? I'll learn to look for HDD activity to read my system better – Joakim Tall – 2013-10-24T15:01:34.713

Answers

It's all about having enough RAM and the speed of your RAM and HDD.

Consider these specs since you did not provide any:

OS:          Windows 7 64-bit
CPU:         Core 2 duo 2GHz
RAM:         4GB PC2 5300
HDD:         500GB 5400 RPM
VRAM on HDD: 8GB (virtual RAM or Page File - default size is RAM x2)

Here is a break down of what happens:

OS takes 2GB baseline to just run OS
Open up large app like photoshop
Photoshop needs 1GB which is fine and dandy
Start working on a hi-res image and now you are at 300 layers
Photoshop has been increasing it's RAM consumption to a specified limit set in your preferences (say 3GB)
Windows is like "oh crap, let me offload some non-essential processes to VRAM"
Windows now has 1GB in RAM and 1GB in VRAM
At this point if you open a web browser then it will be quite slow to open it
This is because items in VRAM are frequently accessed by the OS so your HDD is choking on regular Windows processes
Save work and close photoshop
RAM is FREE!!!
Windows has to move it's processes from VRAM back to regular RAM which is the slowdown that you describe
5400RPM HDD is dirt slow compared to RAM so the HDD is the bottleneck until it is no longer being used for VRAM

You can track your HDD activity by using Windows Performance Monitor: http://blogs.technet.com/b/askcore/archive/2012/03/16/windows-performance-monitor-disk-counters-explained.aspx

MonkeyZeus

Posted 2013-10-23T14:24:32.247

Reputation: 7 101

Very clear answer, thanks. I will learn to read the HDD activity and relate that to ram/vram transfer as well. – Joakim Tall – 2013-10-24T14:58:57.107

I'm glad my post was helpful to you! After reading the comments above I realize I may have used the wrong term (interchangeably). The VRAM I was referring to is also known as the Page File which is a section of your HDD reserved for memory offload. It's default size if double your real RAM. I will update the post for future visitors. – MonkeyZeus – 2013-10-24T15:11:12.480

Best answer I can give is use Process Explorer to look more deeply into what is running. It's far more in-depth than the usual Task Manager etc:

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

IOWCGT

Posted 2013-10-23T14:24:32.247

Reputation: 11