10 tips for troubleshooting PC system slowdowns

When PC performance slows to a crawl, a systematic troubleshooting plan will help you zero in on the cause. Deb Shinder runs through likely culprits and describes steps you can take to improve system performance.

Windows 7 has been out for almost a year, and the PCs you bought right after its release may be slowing down now. User complaints are minimal when new PCs are rolled out. They start up quickly, and programs seem to open in a snap. But over time, users begin to notice that their systems are slower or hang up more and more often. While the possible causes of system slowdown are endless, this article identifies 10 common troubleshooting areas you should examine before you consider drastic steps such as reformatting and reimaging or buying new computers.

Note: This article is also available as a PDF download.

1: Processor overheating

Chipmakers have recently been working to make processors more efficient, which means they generate less heat. Nonetheless, some modern processors still generate a lot of heat. That's why all processors require some sort of cooling element, typically a fan of some type. A system's Thermal Design Point (TDP) rating indicates, in watts, how much heat it can safely dissipate without exceeding the maximum temperature for the chip. When the processor temperature goes over spec, the system can slow down or run erratically (lock up) or may simply reboot. The processor fan may fail for several reasons:

  • Dust is preventing the fan from spinning smoothly.
  • The fan motor has failed.
  • The fan bearings are loose and jiggling.

Often, you can tell if there is a fan problem by listening and/or touching the computer. A fan that has loose bearings starts jiggling and vibrates the case, making a characteristic noise. As time goes by, the sounds and vibrations will become so prominent that you'll change the fan out just to regain some peace and quiet.

You don't always need to replace the fan. If it is covered with dust, you can often spray away the dust with compressed air. But even though you might get the fan running again, its life span has likely been reduced because of the overwork. You should keep an extra fan in reserve in case of failure.

Processors may also overheat because the heat sink is not properly placed above the processor or the thermal paste is not of good quality or was applied incorrectly (or not at all) when the system was built. This is more likely to be a problem with home-built systems but can happen with commercially manufactured ones as well. The paste can break down over time, and you may need to reapply it.

Case design is another element that can contribute to or help prevent overheating. Cases with extra fans, better vents, and adequate room inside for good airflow may cost more but can provide superior cooling performance. Small cases that squeeze components together can cause overheating. For this reason, laptops with powerful processors are prone to overheating.


Another common reason for processor overheating is overclocking. Until heat begins to take its toll, overclocking does allow for significant performance improvements. Because processor overclocking can really cook a processor, most dedicated overclockers do not use regular processor fans. Instead, they use complex -- and expensive -- water-cooling systems. For more information on overclocking, check out overclockers.com.

Overheating can also be caused by the external temperature (that is, the temperature in the room). Computers no longer have to be kept in cold rooms as they did in the early days of computing, but if the room temperature goes above 80, you may find your computers exhibiting the symptoms of overheating. If the temperature is uncomfortable for you, it's probably too high for your computers. Adequate ventilation is also important.

Most computers today have an option to display the CPU temperature in the BIOS. There are also a number of utilities that will track the temperature of your processor and case, such as Core Temp. If you want to look for other such utilities, check out TechRepublic's software library and use the search term "temperature."

2: Bad RAM

Several situations can lead to RAM-related performance problems with a particular machine:

  • RAM timing is slower than optimal machine spec.
  • RAM has minor flaws that appear only on detailed testing.
  • RAM is overheating.
  • There is insufficient RAM.

In the old days of Fast Page RAM, buying new RAM for your computer was a simple affair. You just needed to know what speed your motherboard supported and the maximum each slot would take. Today, there are many types and speeds of RAM, and the better motherboards may be tolerant of using RAM that does not match the motherboard's maximum specs. For example, your motherboard may support PC133 RAM but will still work with PC100 RAM. But be aware that you may see performance decreases if you install RAM that is slower than the maximum spec. Some motherboards will even allow you to mix speeds but will default to the slowest RAM installed.

Minor flaws in RAM chips can lead to system slowdowns and instability. The least expensive chips often have minor flaws that will cause your system to slow down or Blue Screen intermittently. Although built-in mechanisms may allow the system to keep working, there is a performance hit when it has to deal with flawed RAM chips.

In the past, no one worried about RAM chips getting hot, because they didn't seem to generate much heat. But that's changed with newer RAM types, especially SDRAM. To check for overheating, open your computer's case, power down, and pull the plug out. Ground yourself and touch the plastic on one of your RAM chips. Ouch! They get pretty hot. If you find that your RAM chips are overheating, you should consider buying a separate fan to cool your memory. If your motherboard doesn't support a RAM fan, you might be able to get enough additional cooling by installing a fan card that plugs in to a PCI slot.

Of course, one common reason for poor performance that's related to RAM is simply not having enough of it. Modern operating systems such as Windows 7 and today's resource-hungry applications, combined with our increasing tendency toward extreme multitasking, result in a need for more RAM. The minimal specified system requirements may not cut it if you're doing lots of multimedia or running other memory-intensive applications. 32-bit Windows is limited to using 4 GB of RAM, but 64-bit Windows 7 can handle from 8 to 192 GB, depending on the edition. If your system allows, adding more RAM can often increase performance.

3: Hard disk issues

Traditional hard drives are mechanical devices that eventually wear out. There are many signs of imminent failure before a hard disk finally gives up. Some of these signs include:

  • Slow access times on the affected drive.
  • An increasing number of bad sectors when running scandisk and chkdsk.
  • Unexplained Blue Screens.
  • Intermittent boot failures.
  • An "Imminent Hard Disk Failure" warning.

Detecting a failing hard disk can be tricky because the early signs are subtle. Experienced computer professionals can often hear a change in the normal disk spin. After the disk deteriorates further, you'll see the system slow to a crawl. Write processes will take a long time as the system tries to find good blocks to write to. (This will occur if you're using a robust file system such as NTFS; other file systems will likely Blue Screen the computer.)

When you notice the system slowing down, run scandisk or chkdsk, depending on your operating system. If you notice a bad sector where a good sector existed earlier, that's a clue that the disk is going bad. Back up the data on the disk and prepare for it to fail soon. Make sure you have a spare disk ready so you can replace it when it fails or replace the disk as soon as you notice the early signs of failure.

Disk noise and scandisk/chkdsk are your best indicators for identifying a failing drive that's leading to a system slowdown. However, if you are managing a system remotely, or you can't take the system down for a full chkdsk/R, you can use tools that monitor disk health, such as Executive Software's DiskAlert.

You may also get a warning message from SMART hard drives that failure is imminent. Sometimes, you'll get these warnings when the hard drive is fine, due to problems with the hard drive device driver, the chipset driver, or the way the BIOS interfaces with the drive. Check for newer versions of the drivers and BIOS firmware.

Even if it's operating properly, your hard disk may be a bottleneck that's slowing down the rest of your system. See the next item for more information on what you can do about that.

4: Disk type and interface

Once upon a time, buying a hard drive to work with your system was easy. Today, things are more complicated, with many types of drives available, offering differing levels of performance. Most modern motherboards will support more than one type.

For best performance, you may want to dump the old IDE PATA type drives and upgrade to SATA, which comes in several speeds  from 1.5 Gb/s to 6 Gb/s. Obviously, the faster drives will also be more expensive. Some new computers also have eSATA connectors for attaching a SATA drive externally. Other options for attaching drives externally include USB and Firewire/IEEE 1394.

Slowdowns may be caused by installing programs or often-used files on slow external drives. If you must use external drives for such files, go with the latest version, such as USB 3.0 (which is up to four times faster than USB 2.0) or Firewire 800. If you don't have ports to support the faster version, you can install a card to add support.

New Solid State Drives (SSDs), which generally connect via SATA, can often provide better performance than other drive types, but cost much more per GB of storage space. Windows 7 includes support for TRIM, which optimizes SSD performance. SCSI drives are still around, too, notably in the form of Serial Attached SCSI (SAS) with super fast access times -- but they're expensive and noisy and used primarily for servers.

5: BIOS settings

One frequently ignored cause of system slowdown is the machine's BIOS settings. Most people accept the BIOS settings as they were configured in the factory and leave them as is. However, slowdowns may occur if the BIOS settings do not match the optimal machine configuration. Often, you can improve machine performance by researching your motherboard's optimal BIOS settings, which may not be the same as the factory defaults.

There is no centralized database of optimal BIOS settings, but you can employ a search engine such as Google or Bing and use your motherboard name and BIOS as keywords to find the correct settings.

6: Windows services

Many Windows services are enabled by default. A lot of these services, however, are not required for your machine to run properly. You should review the services running on your Windows XP/Vista/7 computer and disable those that you don't need.

One way to see which services are running is to use the Services applet found in the Administrative Tools menu. In Windows 7, click Start and type "Services" in the search box, then select Component Services. In the console's left pane, click Services (Local) to display the list of services, shown in Figure A.

Figure A

Use the Component Services console to identify the services running on your system.
Important information contained in the Services console includes the service Name, Status, and Startup Type. You can get more details on a service by double-clicking on it to bring up the service's Properties, shown in Figure B.

Figure B

The Properties sheet for the service provides detailed information.

You can stop the service by clicking the Stop button. If you are sure that you don't need the service, click the down arrow in the Startup Type drop-down list box and set the service to Disabled. If you are not sure if you need the service, change the Startup Type to Manual. Then you'll have the option of manually starting the service if you find that you need it.

Another way of controlling which services start is using the msconfig utility (see Figure C). In Windows 7, click Start and in the search box, type msconfig. Click msconfig.exe.

Figure C

Use the System Configuration utility to control the behavior of services.

Note that some secure Microsoft services cannot be disabled. These are considered essential for running the computer. For a list of some Windows 7 services you may be able to disable, see Disable unwanted services and speed up Windows 7.

7: Runaway processes

Runaway processes take up all of the processors' cycles. The usual suspects are badly written device drivers and legacy software installed on a newer operating system. You can identify a runaway process by looking at the process list in the Windows Task Manager (see Figure D). Any process that takes almost 100 percent of the processing time is likely a runaway process.

Figure D

Use the Task Manager to identify processes that are slowing the system.

We see an exception to this rule, however, if we click the button to Show Processes From All Users. On a smoothly running system, the System Idle Process should be consuming the majority of the processor cycles most of the time. If any other process were to take up 98 percent of the processor cycles, you might have a runaway process.

If you do find a runaway process, you can right-click it and click the End Process command. You may need to stop some processes, such as runaway system services, from the Services console. If you can't stop the service using the console, you may need to reboot the system. Sometimes a hard reboot is required.

For more detailed information about running processes, check out Process Explorer 12.04, shown in Figure E. This is a handy little utility written by Mark Russinovich that includes powerful search capabilities.

Figure E

Process Explorer gives you more detailed information about running processes.
8: Disk fragmentation

As files are added, deleted, and changed on a disk, the contents of the file can become spread across sectors located in disparate regions of the disk. This is file fragmentation. All Windows operating systems subsequent to Windows NT have built-in disk defragmentation tools, but there are also third -party programs available that give you more options.

If you have traditional hard disks, disk fragmentation can significantly slow down your machine. The disk heads must move back and forth while seeking all the fragments of a file. A common cause of disk fragmentation is a disk that is too full. You should keep 20 percent to 25 percent of your hard disk space free to minimize file fragmentation and to improve the defragmenter's ability to defrag the disk. So if a disk is too full, move some files off the drive and restart the defragmenter.

Note that SSDs work differently and can access any location on the drive in essentially the same amount of time. Thus, they don't need to be defragmented.

9: Background applications

Have you ever visited an end user's desktop and noticed a dozen icons in the system tray? Each icon represents a process running in either the foreground or background. Most of them are running in the background, so the users may not be aware that they are running 20+ applications at the same time.

This is due to applications starting up automatically in the background. You can find these programs in the Startup tab of the System Configuration utility, as shown in Figure F. Uncheck the box to disable the program from starting at bootup.

Figure F

You can disable programs from starting when you boot Windows.
10: File system issues and display options

Some file systems work better than others for large disk partitions. Windows 7 should always use the NTFS file system for best performance.

Cleaning up the file system will also help speed performance. You can use the Disk Cleanup tool to:

  • Remove temporary Internet files.
  • Remove downloaded program files (such as Microsoft ActiveX controls and Java applets).
  • Empty the Recycle Bin.
  • Remove Windows temporary files such as error reports.
  • Remove optional Windows components you don't use.
  • Remove installed programs you no longer use.
  • Remove unused restore points and shadow copies from System Restore.

To run Disk Cleanup in Windows 7, click Start and type "Disk Cleanup" in the search box. Select the drive you want to clean up.

Another way to increase performance is by turning off some of the visual effects that make Windows 7 look cool but use valuable system resources. In Control Panel, click the System applet and in the left pane, click Advanced System Settings. Under Performance, click the Settings button and then the Visual Effects tab. Here, you can disable selected Aero effects or just click Adjust For Best Performance, as shown in Figure G, which disables them all.

Figure G

You can turn off selected (or all) visual effects to increase performance.


When troubleshooting a system slowdown, you should always look for potential hardware problems first. Then, investigate the common software problems. If you use a systematic troubleshooting plan, you should be able to improve the performance of most computers suffering from system slowdown.


Debra Littlejohn Shinder, MCSE, MVP is a technology consultant, trainer, and writer who has authored a number of books on computer operating systems, networking, and security. Deb is a tech editor, developmental editor, and contributor to over 20 add...


Very nice article shared. When I faced this problem. I tried Ninja TuneUp utility which had solved all my problem of slow PC. I found almost all the features covered above in this utility.


I agree with these points but we need a single solution of all kind of pc problems in single click. Their are various computer problems like pc slow, malware, spyware and viruses with errors harm to the computer and their stored information. So can you offers any pc optimizer software like http://www.arridepcoptimizer.com to manage these all problems. 


It improves speed if you have install and uninstall many software.


Many clients load freeware tools to 'ehance thier computing experience'. These tools often add additional 'features' that if not unselected installs a myriad of virus scanners, tool bars and gadgets. Note well, that these additions may or may not conflict with existing installation/configuration. Most end users select default installation options and take no notice of the potential impact, leaving a technician to resolve [PC system slowdowns]


Would someone please show me how to remove Windows temporary files such as error reports?Thanks


In this document at point 3) is a link to "http://www.diskeeper.com/support/techsupport.aspx". When I accessed it: "Reported Web Forgery! This web page at www.diskeeper.com has been reported as a web forgery and has been blocked based on your security preferences. Web forgeries are designed to trick you into revealing personal or financial information by imitating sources you may trust. Entering any information on this web page may result in identity theft or other fraud." There is any malware?


For speed and effeciency....don't assume some common flaws with your system.


This may sound bizarre - it's only on one PC that I've experienced it, and it's too early after diagnosis to be 100% certain I've solved the problem permanently - but here goes. On a fast desktop machine (i7 & SSD hard drive, Win7 64-bit) I was encountering a progressive slowdown during any Windows session of certain explorer functions. For example, certain dialog boxes that I invoke hundreds of times a day (e.g. open/save on UltraEdit or Snagit editor) would take longer and longer to load, the longer the session had been going on. They would snap back after a reboot, but then the whole cycle would repeat. Nothing else was acting slow. Process explorer, performance monitor, etc. - nothing I tried could pinpoint any kind of process or service as being responsible, there was no drag on CPU or ram, event viewer showed nothing, etc. Chkdsk and memory checks all okay. But as far as the affected explorer/shell functions, I felt like I was back in Windows 98 and running out of resources! I finally traced it to some mix of the illuminated USB keyboard I was using plus device manager settings for USB hubs and/or the power options settings for USB selective suspend. Reverting to a plain PS2 basic keyboard fixed the problem entirely. Disabling USB hub suspend and/or USB selective suspend also mostly fixes it even with the problematic keyboard attached. Anybody else run into problems traceable to peripherals and the ports they attach to?

Gis Bun
Gis Bun

If not mentioned, you can add garbage left behind from old installations. As an example, you used Motorola Phone Tools but ditched the phone and software when you switched to a BlackBerry Bold 9700. Problem is that the Motorola phone software was removed but junk is left behind. If you use Microsoft/Sysinternal's AutoRuns you can see which garbage is left behind that is loading but may not be used at all.


I found interesting the points given by Debra. For routine speeduping a system I do the following steps, in the order given: 1. Make sure there are no virus and no malware present. Use AV and AM software. Tools I like are NOD32, SpyBot S&D, Malwarebytes AM. Step "Kick bugs out". 2. Clean all debris with tools like CCleaner or R-Wipe&Clean. Step "Take a bath". 3. Clean the Registry with tools like RegScrub, Registry Booster or other proven tool. Ideally that tool should also be able to defragment the registry. Step "Comb nicely". 4. There is another step which I found out that speed up systems in no negligible way: to wipe the MFT, which becomes huge innecesarily and makes windows loose more time looking for file addresses slowing everything. The tool I use is R-Wipe&Clean. This is a slow process, can take many hours but the result is worth the pain. 5. Last step is to defrag hard drives/partitions. The tool I like is O&ODefrag. Step "The final makeup". Best regards, Roberto


I looked up the author, and while she has an MCSE (big deal), it appears that she has no field experience. Anyone can tack a bunch of letters for "certifications" after their name, but unless those certifications are tested in the crucible of field experience, experience that gives a technician the skills to assess the user, the environment, and the unique "ecosystem" of EVERY machine, they are useless. As for me, twenty-three years in the field working on everything from the old ATs to AS400s, on OSes from Win 3.1 to the most recent iterations of Windows, the Mac OS and various Linux distros; extensive experience with more types of shrink-wrapped, Open Souce, freeware, and full on FOSS apps than I can count; designing, installing, and PD'ing a variety of clusters, network scenarios, and environments, has left me with a long list of very satisfied clients. T This blogger is a poser, yet another sad example of the worst the internet has to offer as it has become a frontier overrun with self-defined, shamelessly self-promoting "experts." If you don't believe me, read her resume: http://www.shinder.net/debres.htm I guess I am too busy plying my trade to hawk myself and endlessly blog regarding topics about which I really know very little.


OK--under Windows Services--does anyone out there know what PC Angel is? It's the only "service" I can't figure out what it is and whether it should be "automatic" or "manual" or "stopped" or what... My other question: if you change a service from automatic to manual, what tells you you need to turn it on?


imho, PC slow downs on your stated Win7 1 year old PC seem slanted to mostly hardware related issues. IF you had used an 'older' machine (3-10 years) as your refrence, the article has more merit. Your minor mentioning of [non-mafacturer (added)]legacy software installation issues does have merit. If the software came on the PC from the factory, and the PC was fast on day one, thier software installation can be ignored as a slowness issue. Slowdown PC issues seen by many technicians are malwares/viruses/PUPs or possibly user installed non-WIN7 compatible [legacy] software. And yes, users usually do not perform routine file and disk maintenance. Many users do not modify the hardware on thier PCs, so slowness due to hardware & driver misconfigurations are 'usually' not to blame. Your example of mismatched RAM from the factory is highly unlikely. I also doubt, seriously, if any PC sold in the last year has a PATA IDE drive installed; it is hard enough to find a new ATA6 IDE drive, in the current marked. Factory set BIOS is another. If it came from the factory with default settings, were unmodified, AND was fast at day one, then BIOS issues are also unlikely. Overheating issues are of significance, many are due to user ignorance or neglect; e.g. changing BIOS settings, room temperature, PC shoved in a non-vented desk cubby, or floor mounted in a dusty / furry pet environment or placing a notebook [formerly laptop]on one's lap or bed or carpet. However, a one year old desktop or mobile computer from the factory, having a failure from dried thermal paste is almost blasphemous, especially since many mfgs. use silicone thermal pads and thermal epoxy. I agree with many of your hardware failure issues and resolutions in much older PCs and/or user modified ones. As I said at the beginning, this article does apply for older, kit form [bundled parts] or user modified computers.


Take a look in Regedit at: HKLM/Software/Microsoft/Windows/CurrentVersion/Run ...and the same folder in HKCU. Get rid of anything that?s not related to your antivirus, printer, sound card, graphics (or any other hardware unless you don?t use it), network tools or database servers. Also, you may wish to take a look through your scheduled tasks - this is in (Administrative Tools in Vista/7) And finally, empty your temp folders (put this in a text file and rename the .txt to .bat: DEL /q "%userprofile%\Cookies\*.*" DEL /q "%userprofile%\Local Settings\Temp\*.*" IF EXIST "%userprofile%\Local Settings\History\History.IE5" GOTO HistoryIE5 DEL /q "%userprofile%\Local Settings\History\*.*" :TempInternet IF EXIST "%UserProfile%\Local Settings\Temporary Internet Files\Content.IE5" GOTO ContentIE5 DEL /q "%userprofile%\Local Settings\Temporary Internet Files\*.*" GOTO UsrComplete :HistoryIE5 DEL /q "%userprofile%\Local Settings\History\History.IE5\*.*" GOTO TempInternet :ContentIE5 DEL /q "%UserProfile%\Local Settings\Temporary Internet Files\Content.IE5\*.*" DEL /q "%Temp%\*.*" RD /s /q "%SystemRoot%\$NtServicePackUninstall$" FOR /f "delims=" %%a in ('dir/ad/b %systemroot%\$NtUninstall*') do (rd /s /q "%systemroot%\%%a") For Vista/7 users: DEL /q "%LocalAppData%\Temp\*.*" DEL /q "%LocalAppData%\Microsoft\Windows\Temporary Internet Files\*.*" DEL /q "%LocalAppData%\Microsoft\Windows\History\*.*" See about clearing your page file aswell and if you have any animations on your display settings (especially an animated gif desktop background) get rid. Finally, Windows XP needs an absolute minimum of 256MB RAM to run itself alone, with all the latest updates. I recommend 1GB for standard users or 2GB for gamers. PC2-6400 or faster is ideal with low latencies (4 or 5), but if you have an old system, PC-3200 should be your choice. Older still, you'll want to overclock your PC-133 to 200 MHz or faster, depending on if your latencies are low (2 or 2.5) and if your processor is stable enough.


How about windows just slowing down until you reload the OS.


There are so many issues with this blog post I do not even know where to begin. First, the order of issues is completely out of whack. You start with simple, non-hardware based issues, after ensuring that fans are running and all the intakes and outflows are clear. Especially for a home user, going straight to a CPU or RAM issue is flat out stupid. Number 10 should be number 1 (although adjusting for "best" performance is really not a good idea. A REAL tech does a custom adjust, so that things like smooth screen fonts are not blown away), number 8 number 2, etc. You do not even mention fragmentation until number 8. Are you aware that a seriously fragmented hard drive runs harder because of the way FAT and NTSF "manages," and I use that term loosely, files, thus reducing drive life, and that a disk does not have to be nearly full to be badly fragmented? You do not mention putting dedicated heat sinks on the RAM. A novice should never screw around with thermal paste (and there are different types). The norm, alas, is to OVER apply. Do you know how it is supposed to work? It is designed to spread, with the pressure of the heat sink and the heat of use, to a layer so thin it fills the microscopic gaps between the proc and the heat sink, producing an almost perfect mating. Applied in excess, it oozes out and can cause serious damage to the proc and socket. This makes me wonder why the heck I am not writing articles, and how the heck this author was able to wrangle a forum.


This article is written wrong or the numbering is backwards. The first things people should consider when a system starts running slow is not to check and see if its overheating. That is a fairly rare occurrence. While it doesn't come out and directly "rank" these issues, but by numbering each point it does so indirectly.


Not bad. Pretty well written and you covered most of the common problems for pc slowdowns


When the hard disk overheats in a laptop, it may appear that the laptop has 'frozen' but then may come back after a while. I've used the speedfan utility (almico.com) to monitor the hard disk temp after I noticed Spinrite 6 pausing "due to overheating" message when a Dell C600 reached 53C on the internal temp sensor on the laptop's hard disk. I pulled the battery and cd-rom modules, put the battery into the right side and positioned some small fans to blow across the hard disk. This reduced the temp to 30C rather quickly and spinrite completed. A full norton AV scan on other Dell laptops I've had will easily raise the temp into the upper 40C range. Putting a small fan blowing across the laptop has always reduced the temp of both the harddisk and core/video temps.


Another cause of a slowdown is those who perform a RAM upgrade and are using customized Virtual Settings. Set to System Managed or increase your virtual settings.

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