A machine is described as being "really slow" or "freezing". How can I troubleshoot/resolve this issue? What should be the first steps to take?


17 Answers 17


Assuming you are using a Windows OS...

Things to check:

  1. PC has 10% at least of free disk space
  2. PC has at least 1 GB of RAM for Windows XP and 2 GB for Windows Vista
  3. If there are any hanging programs or drivers.
  4. Corrupt system files. If that is so, run sfc /scannow in cmd and let it replace any corrupt system files. It may ask for your Windows CD. Or, if it is seriously damaged then perform a Windows XP repair install or Windows Vista repair install
  5. A badly corrupted file system. This is from experience rather than knowledge. Run chkdsk /r in the command prompt.
  6. Due to the way Windows handles files, it will in inevitably get slow over time. Your MFT structure gets bigger and bigger over time. The only cure is a fresh install.
  7. Malware. Download and run HijackThis, and then post the log here. It'll give us a decent idea of what's running and what could be hogging all your memory/CPU.
  • 23
    Are you sure about your defrag comment? I recently defragged an NTFS file system that was very well used, almost full and had not been defragged in many years and noticed a huge performance improvement. Perhaps the "no difference" comment applies to the most common cases where a disk is generally underutilised?
    – luapyad
    Aug 23, 2009 at 4:29
  • 1
    Defragmentation will run once a week on schedule anyway but yes, obsessive-compulsive defragmenting won't be of much use. If anything one only wastes time. Also, if you don't fill your disk further than like 75 percent it's unlikely fragmentation ever causes a performance problem.
    – Joey
    Aug 24, 2009 at 14:53
  • 4
    WRT defrag, it depends. I used to daily work in an app that depended upon two files, one ~65MB in size and another ~2GB in size. When that app became "really slow", I went and ran a defrag analysis and discovered that, usually, one/both of those files were ~85% fragmented. After running defrag, the app sped up significantly.
    – J. Polfer
    Aug 24, 2009 at 15:01
  • 4
    "Due to the way Windows handles files, it will in inevitably get slow over time." -> Do you have any reference for that? I know NTFS uses a MFT structure, but I never heard that this will necessarily always cause Windows to become slower.
    – sleske
    Dec 9, 2010 at 21:58
  • 2
    I know this is old, but does anyone have reference to the "inevitable" slowing down of Windows due to MFT structure (with the only cure being a reformat)? I don't understand how it would only be a "one way street", with the only solution being a complete wipe and reinstall. It was my understanding that the days of "annual" Windows reformats to keep things snappy went away with the XP-era. Jul 4, 2013 at 8:44

Most system freezes (where you can't use hot-keys like CTRL+ALT+DEL) are caused by hanging drivers,
so you will have to either replace the device or update the driver. Troubleshooting can be done:

  1. Download Windows Performance Analyzer for your Windows version.
  2. Install the software on your system.
  3. Open a command prompt as administrator, and copy paste the next command:

    xperf -start perf!GeneralProfiles.InBuffer && timeout -1 && xperf -stop perf!GeneralProfiles.InBuffer myTrace.etl
  4. Press ENTER once to start the command, now you will have to wait till your system hangs.
    You can do whatever you want to. Please no heavy activity like gaming or private things...

  5. Right after your system stops hanging you go to the console and press ENTER.
  6. After waiting some time a log file myTrace.etl will be produced, compress this to a zip file.
  7. Put this compressed version of the file somewhere online (perhaps 2shared).
  8. Share the link here, I will do an attempt to find and show you the cause of your problem.
  9. OR troubleshoot the trace yourself using instructions found here, start with step 6 - 7.
  • 10
    This doesn't scale very well, having people just upload an xperf trace. Is there any way you could edit this to include some info on how people can use that information to debug the system themselves?
    – nhinkle
    Jan 5, 2012 at 6:24
  • 1
    @nhinkle: This outlines the program out in a bit of detail, however it boils down to just opening the trace and looking around. If a person isn't smart enough of actually doing some self study on the things seen there, he should probably not be debugging traces. Debugging is really something you should use Google extensively for. When a program crashed, I can see the data that was on the stack. Can you? Of course one can ask how a specific thing exactly works or what a specific things means. Jan 5, 2012 at 11:24
  • But in general, you are on your own. Writing a complete guide on how to use XPerf would detriment away from the intention of this post, which is to get the actual problem resolved. Please note that a compressed Xperf trace is very small, so it does scale very well compared to crash dumps. And oh well, those would even be harder to explain how to debug them (it requires a good understanding of the internals of a computer). Google is your friend, if you read documentation you can even access it from a Memory window. Jan 5, 2012 at 11:30
  • 1
    Also, it depends from case from case what you have to look for. One time, I'm walking down the stack tree of a process to find out that a firewall is messing up my Visual Studio debugger. Another time, I just look at the DPC calls for someone that send me a dump through a mail, another time I look for the biggest I/O consumer for someone on the SU chat. You need an understanding to actually know what you need to look for, if I need to cover most of these cases I would have the longest post on SU. Although most of that can otherwise be reached by simply researching and learning. Jan 5, 2012 at 11:40
  • However, feel free to ask a question on the actual use of XPerf as well as a community wiki that summarizes what to do when specific cases arise. It might help as a start for beginners that don't have a clue what they are doing. However, I currently don't have the time and willingness to do this here and now.... Excuse me for the length of my comments, but I thought a single comment is insufficient to get the idea. Jan 5, 2012 at 11:42

First off, I check what is automatically started when the machine boots up.

  • Autoruns
  • Registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  • msconfig
  • Run -> services.msc This will list all the services that are started up when your machine turns on. You can manage all of them here from this MMC snap-in.
  • Scheduled Tasks

I will then run process explorer and see what is running after it is booted and see what hogs up a lot of memory and CPU.

I will then make sure all the drivers are up to date, same with anti-virus, windows update and other critical applications such as web browsers, java, flash, etc.

Then I will defrag their hard drive if it needs to be done.

Sometimes I will clear out their web browser history and cookies and also clean out their temp folders.

I will also look through the event viewer to see if there are any errors being reported and check into them if they do.

If all else fails and the system will support it, a RAM upgrade may be in order.


(assuming for a moment, we are talking about Windows)

If your computer is suddenly running slow (i.e. you don't just have a slow computer), I would check the Windows Task Manager.

  • Type Ctrl-Alt-Delete to bring up the Task Manager.
  • Select the 'Processes' tab at the top to bring up the list of all processes running on the computer.
  • Click on the 'CPU' column at the top of the process window... twice (to sort processes with max CPU usage first).
  • See if anything (other than "System Idle Process") is taking more than a few percent CPU consistently.

Virus scanners or other background services can sometimes become overzealous in using system resources. Sometimes an application can enter a race condition where it gets "stuck" in some loop of code it just runs continuously. Then, sometimes, you just have some application you forgot about taking up all your CPU time.

The Task Manager should tell you if anything like this is going on.

  • 1
    I'd also google any processes you're unsure of to confirm if they are needed/necessary and then use msconfig/HiJackThis to stop them starting up. Aug 23, 2009 at 11:25
  • 2
    MSCONFIG is not a startup manager but a troubleshooting utility and therefore better left alone. HiJackThis i don't trust anymore since TrendMicro laid their hands on it.
    – Molly7244
    Sep 16, 2009 at 23:08

In this order usually...

  • Hardware - Hardware is the fastest and easiest thing to check that is usually the culprit. Memory is cheap these days, seeing people that still have 128 MB and 256 MB installed makes me want to cry. With Moore's law being so apparent in the hardware world, CPUs that are still blazing fast and can be bought very cheap as well.
  • Software clutter - the amount of software installed and running upon system startup impacts performance big time. There may also be malicious software slowing you down.
  • Updated drivers - these can give your machine big performance boosts.

A good pass of a defragmentation program, CCleaner, and a virus scannner and malware scanner is beneficial as well.


To see if your machine is going to be slow, check

  • Amount of memory
  • Speed of CPU
  • Disk space available

There are many third-party tools available that give you information on your computer, but to do this quite easily without those you can use the Windows Task Manager.

To open "Task Manager"

  • In the task bar, right click the mouse then select "Task Manager"

On the performance tab you will see how 'busy' your CPU is also how much physical memory is available.

If CPU is consistently above 10% and there is less than 500000 K of memory available your machine is probably going to be running slowly.

Also if your hard drive is full, this could lead to poor performance. You should aim to have at least 15% of free space.

To check this, open Windows Explorer, you can do this by

  • At the same time, press the windows Key followed by the letter e

Select the C: drive with a mouse click. Then right click and select properties - this will tell you how much free/used space you have on your hard drive.


Not without knowing what is causing the freezing as it is not actually causing a crash.

This sounds like at first guess that it is a hardware interrupt / bad device driver causing this, as for banging the keyboard - this is most likely just down to luck.

Try first looking through your system event log for any errors or warnings that could be driver related.

Next either uninstall the driver or if you do not find anything, I would first advise unplugging all extra USB devices as the easiest solution, then if that solves it, plug them in one by one until you find the bad one. If you do not find anything, you may actually need to uninstall drivers.

If you still have errors or want to rule it out earlier, I would advise running a memory test, and going to the command prompt to run a Chkdsk to scan the hard drive for problems.

I used to get this all the time on old machines, 99% of the time it was people buying cheap/unknown brand devices with VERY bad drivers - it gives Windows a bad name. If however you still getting problems after following this, please say and I will try to help further.


Defragment your hard drive. For Windows XP Disk Defragmenter is located at
Start -> Programs -> Accessories -> System tools.

For Windows 7 or Vista see this question.


For another speed boost, disable unnecessary Windows services. There are a few well-trusted databases on what's safe to disable and what's not, for example, The Elder Geek's Services Guide for Windows XP.


In addition to the other suggestions here, I have found that simply emptying the Recycle Bin can make a difference to performance, if I have been filling it with large collections of files.


Personally, I go with the following:

  1. Open Task-manager and sift through all running processes jotting down those that are unncessary and taking special care to check for any suspicious proceses. 99.9% of the time, if you don't recognize a process, just type the name into google and you will get ample information about the nature of the process and wether it's necessary or not.

  2. With the list of procceses in mind, I open up msconfig (type msconfig in the run dialog) and in the start-up tab start unchecking those proccesses that are not neeed in the background. Take care disabling different startup items as sometimes these rely on each other.

  3. Go to Control Panel and once again sift through installed software and uninstall those which the user doesn't need.

  4. I then go through the Services that are running (type services.msc in the run dialog) and either set them to disable or manual depending on the service.

  5. I run a full antivirus and spyware scan on the system and restart.

Now, if the computer hasn't speeded up somewhat, I recommend them to simply let me format the system and start over clean. Because of the nature of windows and all the junk that inevitably forms over years of use, this is usually the only viable solution.

Good luck!


I always check the following...

RAM. Modern OSes are RAM-hungry and the more you have the better off they are.

Hard drive space. Modern OSes are hard drive hungry and the more you have the better off are.

Background processes (e.g. open applications, disk scanning software, virus software, viruses themselves). The more gadgets, widgets, applications, etc., the slower things will be overall. Only keep open what really needs to be open.

Time between reboots. Every OS needs to be rebooted every once in a while.


Assuming a machine used to be running fast, and is now running slow (and it isn't Linux based)....

  1. Restart the machine
  2. Check for viruses and other malware first.
  3. Open Task Manager (or the equivalent) and see what application is monopolizing the CPU or doing a lot of harddrive writes/reads. I may close/kill the app or I would google it and see what the other complaints/solutions are for it.

Other options to consider are:

  1. Malwarebytes Anti-Malware

  2. Raising the amount of virtual memory used by the system

  3. This how to geek guide shows that disk cleanup doesn't really clean-up everything unless you perform a registry tweak. The guide shows how to fix that.

  4. Finally a reinstall of the OS is my final option. Windows likes to keep a lot of crap


That sounds like an unusual circumstance (as many people experience little trouble day-to-day with Windows 7 and your issue sounds quite inconvenient).

Could you provide more detail? Is this a "new" new PC or just one that is new to you (i.e. second hand with Windows 7 newly installed)? Do you know the specification of the PC? Does the problem happen regularly in normal use, intermittently with no obvious pattern, or at specific times like shortly after start-up?

In the absence of more information, a first stab at somewhere to look for the cause of the issue is to check that you drives are healthy by querying their SMART status paramaters with a tool like http://gsmartcontrol.berlios.de/ (available for both Linux and Windows - there are numerous other utilities with similar abilities if this doesn't work well on your PC). A failing drive is quite a common cause of unexpected pauses, as for certain faults the drive will cycle retrying until it manages to read/write what it has been asked to read/write and the user interface seem to hang until the OS gets a response from the drive.

Also check the Windows event logs for around the time(s) the issue is apparent. Most hardware drivers will report unexpected conditions there and Windows itself will report certain driver errors there that the drivers themselves fall over before reporting (older Windows variants would just bluescreen in such circumstances, but newer releases will try restart drivers and log the event when an otherwise "fatal" error condition occurs) - so if the problem is caused by an errant driver or faulty hardware those logs may give useful clues.

  • It is a new PC (not refurbished). There doesn't seem to be any pattern. Hitting the windows key enables the system to operate again until the next time it freezes Nov 1, 2010 at 22:51
  • Could it be a problem with the machine trying to go into sleep or hibernate mode, and failing? Check your event logs around the time the machine pauses or the time you manage to unpause it for errors/warnings/messages regarding this (or other issues). Also check your power management settings to see if the machine is set to sleep/hibernate (uncommon but not completely unheard of for desktop machines). Nov 2, 2010 at 0:38
  • Can you please provide steps to access the event log in windows 7? Nov 4, 2010 at 3:28
  • I don't have a Windows 7 install anywhere to check, but under Vista just typing "event" into the start menu brings up "Event Viewer" which opens the relevant admin snap-in and it is also available under Computer Management in control panel. Nov 4, 2010 at 14:07

In case of Windows, install only those software which you need. Don't mess up your PC with all useless stuff. Check for registry errors and fix them using a good software like regcure or registry booster. Don't forget to check whether your antivirus is updated or not. Outdated antivirus often tends to slow down the system. Use CCleaner to remove the crap. Don't exhaust your RAM by using too many programs in background. Turnoff Windows sidebar or desktop enhancement software if you don't need them. Scan all system by updated virus to make sure it is not infected. Also disk defrag etc. small utilities can be helpful for your PC.


One of the causes of the slowdown, especially at startup, can be Windows trying to restore connection with network share. Configure Registry to prevent it:

Windows Registry Editor Version 5.00


If there's a performance problem, disable all the unneeded services and startups, use a lightweight browser (see memory usage), disable Aero theme, etc.

If you suspect malwares have infected your PC, it is advisable to format you're drive (and not trying to clean it).

Also, USB pendrives can prevent the system to boot. Unplug them.

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