It's these incessant commercials I always see on my TV. "Install our product, and we will make your PC up to 100% faster!" Then they usually go through a few customer use cases (typically involving elderly folk) about how they installed it and found they could read e-mails much quicker and that their startup time was cut in half, their programs loaded quicker, and many more wonderful and seemingly desirable things.

Being a software engineer I am skeptical of these commercials and these products. I understand there can be registry errors (one of the things they say they can fix) and that there could be other programs unnecessarily running on startup which could slow boot time, and a severely fragmented disk which could slow seeking and loading files, but really?

Do these products do anything useful, other than make their developers rich? And furthermore, if they claim to fix registry errors, how do they know what was supposed to be in the registry in the first place on third party software, as far as I know there is no central "this is what a registry should look like" database?

I guess I'm just skeptical about software which claims to be the end-all of software issues. But please, you thoughts?

Question: Do these products provide measurable speed increases or decrease the frequency of crashes/freezes on one's system as a result of using them?

Here are some specific examples:

  • Registry Cleaner

    CleanMyPC Registry Cleaner will check your Windows registry and then remove any incorrect or obsolete information in the registry. Repairing these faulty registry items will allow your PC to run faster and error free.

  • My Clean PC

    Quickly clean your system and increase speed...Prevent annoying screen freezes, crashes and errors.

  • PC Doc Pro

    Get rid of crashes, freezes, and long wait times with our 1-click software right now.

  • 1
    I'm not sure how good this tools are, I'm using a tool for more advanced users -- CCleaner, which let's me actually verify and modify what's being cleaned. I can say that it actually works quite good, although it does get lot of false positives. I imagine that for totally typical setup would do better. Cleaning crap like MyWebSearch and other similar malware does indeed speed up the boot and improves responsiveness significantly.
    – vartec
    Jul 20, 2011 at 14:30
  • 2
    Well, if I wrote a super-simple script that automatically uninstalled all those terrible browser toolbars, I could claim something similar. And the windows registry is indeed s.th. that can slow down your computer. That's why the perceived speed after a complete reinstall is quite great.
    – Lagerbaer
    Jul 20, 2011 at 15:24
  • 2
    Go to Super User. Jul 21, 2011 at 3:00
  • 2
    Here's how this "get rid of crashes" work. I work for a software company. Once in a while I see some Windows API function will not work as I expect and return some very specific error code. Most error codes are also mapped onto user readable messages like "RPC call failed and didn't execute". I see a message like thatand Google it and find lots of "help sites" that promise to "get rid of [the message I'm searching for] errors". Now I'm a software developer and I get that message because there's some limitation that my program doesn't follow. [to be continued]
    – sharptooth
    Jul 21, 2011 at 7:49
  • 1
    [continued] Only me, not the end user can do something - use another function, or change parameters or tweak something else in the program code. End users usually have zero (NULL) chances to "fix" the problem. Yet those "get rid of crashes" sites imply that end users can get something useful.
    – sharptooth
    Jul 21, 2011 at 7:51

1 Answer 1


No software application has yet been devised which can take all possible variations of system configuration into account and make appropriate decisions to optimize a randomly selected computer.

That being said, there are a number of things a user can do which will (generally) improve the responsiveness of their system, the majority of which can be done without any software other than the built-in system tools (defragmenting, etc.)1

One "optimization" which is almost never justified, or entirely safe2, is messing with the Windows Registry. The Windows Registry is not rigidly formatted3 and applications may store data in it in any manner they wish (within the restrictions of the application's security context, of course4.) This free-form construction means that it is all but impossible to definitively tell whether a key is "useless" or "useful" without being intimately familiar with the application that owns it5.

Certainly, applications which "walk" the Registry (that is, proceed from key to subkey in a linear manner looking for a particular key) will suffer speed penalties, and those penalties will become greater in direct proportion to the number of keys the application has to look at in order to find the particular key its looking for (I have no citation for this, but to me it's common sense that looking at each key in turn is slower that just going right to the key you want.) However most applications don't do that, or at least not often, so the penalty doesn't apply to them. This fact, when taken into consideration with the fact the "pruning" the registry can have disastrous results if an error is made6, leaves only the conclusion that whatever gains are to be had by running a registry cleaner/optimizer/defragger/etc. are outweighed by the risks. And this is not even considering that "registry cleaning" has no official definition other than what the Registry cleaner's vendor makes it.

In short, registry optimizers are the modern day snake oil wonder tonic.

The best advice for keeping your computer running at peak efficiency is the same advice as for everything else: take care of it. Don't install every free app you find, run a reputable and up-to-date security application, keep your software and the operating system up-to-date, periodically defrag and chkdsk your hard drives (note that SSD drives require somewhat different care and feeding than mechanical drives,) uninstall an application if you don't use it, and judiciously curtail the number of applications and services which are set to load at start.1


  1. http://www.microsoft.com/athome/setup/optimize.aspx
  2. http://msdn.microsoft.com/en-us/library/ms724871%28v=vs.85%29.aspx
  3. http://msdn.microsoft.com/en-us/library/ms724946%28v=vs.85%29.aspx
  4. http://msdn.microsoft.com/en-us/library/ms724878.aspx
  5. http://msdn.microsoft.com/en-us/magazine/bb985037.aspx
  6. http://support.microsoft.com/kb/256986
  • Doesn't answer the whole question, but offers a great response to "registry cleaners". +1
    – TehShrike
    Jan 28, 2012 at 3:25

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