Windows XP/2k3 and earlier (can't attest to Vista, but suspect it's the same) all appear to become more sluggish over time as applications are installed and uninstalled.

This is not a scientifically tested observation, but more of a learned-through-experience piece of wisdom. (I've always suspected the registry as being behind the issue.)

Does anyone have any concrete evidence of this degradation occurring, or it just an invalid perception of mine?


I don't know what it is with the others here, I haven't met someone that doesn't know what you are talking about. There are many reasons for it, but some have not been identified.

I'll start with a better description for those that don't know. A fresh install of Windows will boot in under 1min. Over a period of 6 months the computer's boot time will not only slow but the entire experience of the OS is not on par with a clean slate. If you ever reinstall windows after 1 year of use you are sure to see the difference.

Reasons for the slow down have been attributed to increased clutter in your registry, and fragmentation of your disk. You have noticed that uninstalling does not help, this is in part because everything isn't cleaned from the registry. Ad-ware can be an issue, but this is usually not the cause.

You can get registry cleaners, defreg, and remove ad-ware, but even this will not return the system to its original speed, no one has come up with a reasonable explanation for this, it just is.

Note to others, this is not a normal behavior for an OS that is being used, I have been using Linux for 4 years, while this wasn't without re-installation, there had never been performance increase from a re-install or a slowdown from large amounts of installing/uninstalling programs.


On the other hand, even a clean reinstall won't make an old computer feel as fast as it did when it were new; because we expect more and more. Ten years ago you used smaller simpler applications, wich used less CPU and RAM, today maybe even your word processor is using hardware accelerated 3D effects...

This, I beleave, is the number one cause of this (often not measurable) feeling that the computer is getting slower. (Of course on a windows system there may be measureable differences before and after reinstallation. Windows is a complex system doing a lot of things in the background, and some processes may not do a good enough job cleaning up after themselves. Windows have been criticized for many things during the years, and being to effective and not wasting resources is not one of them) ;P


I recently re-installed XP using an install CD purchased in 2002; boot time was around 30 seconds. By the time I had finished installing all the updates and service packs, boot time had increased to around 2 minutes.


It would help to be bit more specific about the situation (how much slower does what get, what are you doing to your machine, etc.)?

I would expect it to get slower as it grows: most data structures work this way.

Make sure your disk is defragmented.

If you install a lot of software, it's common to get a lot of registry entries. Depending on the software, it may not get around to cleaning up its messes when you uninstall it.

Check for adware, viruses, etc.

Like ahockley, I've found that XP and Vista (with recent service packs) are quite stable--at least as stable as Linux PCs that I manage.


No-no, It's bit rot! ;)

Seriously, a windows installation does not degrade much if you don't use it at all. But a computer you're using will much likely have more and more software installed, many of wich automatically set themselves up to start running in the background on startup. In fact all computers, no matter what OS, can be expected to run slower as more and more services is running. Windows is perhaps notorious for allowing programs to install themselves in the "startup folder" or similar.

There allso seems to be an apparent loss of responsiveness with many programs installed, even if they are not running; I'm not sure what causes this, but a random guess would be that there is a bit more data to parse through each time a menu is displayed wich subjectively slows the computer down without really impairing the average processing power...


The windows registry, which almost every windows application uses in one way or another can become very bloated with junk data over time. This is especially true when installing and uninstalling many apps. Often applications don't clean up their reg entries after being uninstalled. There are applications out there which attempt to clean up the registry and you can do it by hand with regedit but proceed with caution- destroying an app's registry will ofter break the app and potentially the os. This is just one area to look for performance gains though, hardware could also easily be the blame.


Google for "winrot", I think the sheer number of results will be your "scientific proof"...

And for those who are still living "in denial". Winrot IS REAL...!

I don't even know why you're even questioning this. I think even MSFT have acknowledged it...!


Sadly, we all degrade over time.


There are various patches and updates that Microsoft makes to its software that may play a role here as well as changes in hardware over time.

XP Original requirements for example lists a 128 MB of RAM recommendation that I doubt anyone would try to run XP on that low amount of memory.

My current machines have at least 2 GB of memory which is 16 times that amount and generally I wouldn't run XP on a machine with less than 512 MB of RAM, due to how much memory will get used up as the O/S does all that it does at startup.


I run Windows XP since 2002, and cannot confirm to the performance degradation claims I ofter hear, except for the boot time.

Every 2-3 years I have reinstalled Windows, for various reasons (repartitioning and not wanting to use a partition manager etc.). After a clean install, Windows boots fast and feels snappy. However, after I install all the programs I need, the boot time is considerably longer, but otherwise there is no change in "snappiness", whether I use the same installation for one day or for one year.

A few years ago I read a test from a German computer magazine, where they compared Windows performance before and after running different registry cleaners, and found practically no differences. I would think the experienced performance degradation comes from installing more programs over time, and especially programs, which run on background. However, I don't believe Windows itself degrades the performance.


I suspect that for many people, it's the accumulation of adware. I haven't done a scientific study, though.


With all the machines I use regularly I've not noticed any slow-down from the day I first used them. Some apps are a little slower, but generally that because a new version has some out with some new features. Overall there's not much of a difference.

However, the machines which I get complaints about in the office tend to have a huge list of "services" and other apps running in the background. My machine isn't high-spec but runs quick because I make sure that I don't have a huge process-list; on average I've got <50 processes running. The guys in the office who say "my machine's slow" have, despite my requests, installed this or that and soon they've got ~100 processes running (inc. multiple anti-viruses, yahoo/google toolbars, etc). Even when they do uninstall stuff the crapware they install tends to leave services around or small exes running.

If you're experiencing a slow-down I'd say its time to Start>Run>msconfig and cull the rubbish that's booting when you do.


You've asked for concrete evidence that machines running various versions of MS-Windows OS become more sluggish over time. I have also observed this. There are various reasons as to why that may be the case.

  1. registry clutter
  2. more demanding software
  3. more applications loaded into memory and running
  4. malware
  5. hard disk fragmentation

Here is a simple procedure for obtaining the evidence you requested.

  1. Using a stopwatch, time various operations on a specific machine, especially ones that you anecdotally believe have slowed down.
  2. Reformat your hard disk and re-install enough software to complete the following step.
  3. Using the same equipment as before, perform the same timing experiments

This will give you a concrete answer to everything but reason 2 as a lot of software now updates itself with the most recent copy automatically.


My father still uses his IBM all in one XT, running DOS 5.0, WordPerfect 5.1, and Quicken 6.0 to manage his business expenses. It runs the exact same speed today, as it did 6 years ago, when I first set him up on it.

Of course this avoids much of the possible pitfalls described in other answers, No new software installs, no registry, no extra startup applications.

You might almost consider this a control case.


Others have given specifics, but I think that fundamentally, this is an example of the second law of thermodynamics.

In a system, a process that occurs will tend to increase the total entropy of the universe.

If you're not doing anything to speed Windows up, it will always get more disordered (and therefore slower) over time.


Not sure what you're asking about without any more specifics. Older versions of Windows had some issues, but I've found XP and Vista to be pretty solid, to the point where I can leave them running for a couple weeks without a reboot and don't see any problems. I'm sure that certain software combinations might cause problems, but Windows itself (at least in recent versions) doesn't seem to degrade in performance.


Running software with memory leaks will cause this, as less memory is available for caching. For your average home user, spyware/crapware frequently becomes an issue as well if you're looking at it from this point of view.


Are you sure its not the hardware performance that degrades?

Take some good benchmarks, re-install the system as it was when you first got it, and then measure again. I would be curious to see if the HDD or other components are partly to blame.


Aside from adware, other application developers want to have their application load bootstrappers when windows starts, to reduce the perceived time it takes their application to load, or they want a background service to handle downloading updates etc. Common Examples: Microsoft Office, Google Updater, Adobe Acrobat.

To compare, try opening up msconfig and disabling all startup items and services and then rebooting.


Bugs in applications and DLLs (also know as DLL hell). MS tries to fix the bugs but can't because it would break too many apps. So they create a new version of the DLL with a new function -> DLL gets bigger and needs more RAM, takes longer to link dynamically, etc.

If you're really unlucky, the old code demands a copy of the original DLL to be somewhere, so MS even has to give the fixed DLL a new name. This way, more and more bugs clog your memory, PC swaps more -> slow. Other programs have given up on the DLL hell and bring their own versions of the DLLs which they keep in their install directory. Now, you have to keep several copies of the same DLL in RAM.

Then we have a lot of stuff going on in the background. The virus scanners get slower every day because they need to check for more signatures. Junk piles up in the tmp directory, forcing the drive head to travel bigger distances. It takes longer to scan the directory.


It's not only to do with the registry. When applications are installed, they sometimes install a load of unnecessary junk which even if the programs are unused, then run in the background from start-up. When applications are uninstalled do they always uninstall properly, or do they leave bits of the application and files behind or leave windows still attempting to find, run or use various parts now missing, or have pieces been removed that other programs also depend on? Install and uninstall application programs often enough and eventually Windows itself starts to become unstable and needs a clean install.


When first installed, windows configures disk controllers to use the fastest DMA mode available. If sufficient errors are encountered, the access mode is stepped down. There is no mechanism that tries to use faster modes if things are operating smoothly. Over time, the mode drops further and further, until all disk access is in PIO mode and the computer seems completely broken.

Deleting the controller device forces windows to reconfigure the device using the fastest mode available. A complete re-install causes this to happen.

Pure speculation on my part, but it makes more sense than registry bloat when you consider that people are complaining about bitrot on machines that have gigabytes of excess RAM.

(Certainly additional services and other background processes contribute to slower boot times, but the idea that the performance of the software would degrade without impacting other functions is pretty unlikely)


The problem is that windows does not have a repository for software, linux have all it's software organized by some dictated install software (apt-get etc) while in windows land is each man for itself, you can install anything, anywhere and who watches everyone is the registry. The problem is not Windows itself, but rather how the applications uses the registry. In linux each file of a program has a place to be and the dependencies are handled manually or by some master control software. In windows the guy who made the application has to also make some uninstallation program. Well you usually don't want the user to uninstall your software and if he does that you don't usually care about what happens to him.


I rely on WinDirStat to find large and forgotten files, directories with too many files, and directories with too many directories. That's how I found out about WebsiteCache, by the way.

I use ProcessExplorer to find leaky applications.

I use TcpView to keep TCP/IP connections in check.

I use autoruns to keep start-up apps and services in check.

I really hope I someday find a way to clean up WinSxS folder (does it stand for win-success, or is it what I'm thinking).

With these tools, all is well on Windows XP that was initially installed 3 or 4 years ago.


It primarily has to do with disk fragmentation and an increasing number of services and background processes as additional software is installed.

Vista solves disk fragmentation issues very cleverly: So cleverly that Vista machines tend to actually increase in speed over time. On the other hand, installing lots of services can drag down Vista just like it can XP.

Windows 7 also has the Vista features that prevent the OS from slowing down over time due to fragmentation.

Note that "fragmentation" in this context refers not only to individual files being fragmented but also to collections of files that are loaded at the same time not being together on the disk.


Because then the unwashed masses think their computers are too slow and they need to upgrade to the latest and greatest thing the CompUSA salesman gives them. Which then makes them by a new copy of Windows. Which then = $$$ for MS.