Cleaning the Registry

Because the Registry is so critical to the operation of Windows and is in constant use, its care and maintenance are an essential part of keeping a computer functioning properly. Previous pages have discussed backing up and methods of editing. This article will discuss Registry cleaning and its pros and cons.

Why Clean the Registry?

Recommendations that the Windows Registry should be cleaned on a regular basis are common on the Internet. Almost all of these are echoes of what has been previously written. Most are sales pitches for software. Unfortunately, there seems to be little quantitative evidence one way or the other about possible benefits to recent versions of Windows. The notion that Registries should be cleaned regularly is based more on anecdotal claims of improved performance than on systematic study. However, there are also these three themes supporting the idea that Registry cleaning is beneficial:

  1. The central role of the Registry, the fact that programs constantly access it and often leave behind useless parts when uninstalled, makes it plausible that cleaning would help. In fact, the size of the Registry generally grows over time.
  2. There is the well known phenomenon of "Windows Rot" or "Code Rot". Over a period of time Windows systems slow down or even get unstable.
  3. Back in the days of Windows 95/98 there was substantial anecdotal evidence for the value of periodically cleaning the Registry. This experience has been extrapolated to more recent Window versions.

In the next section, we will examine these points in more detail.

Registry Cleaning Pros and Cons

Although Registry cleaning might seem to be an obvious part of system maintenance, its merits and implementation are not clear-cut. Opinion is divided and many Windows experts advise against it except as a last resort for a badly behaving system.. One who has looked into the matter thoroughly is Ed Bott, author of many Windows books and and a leading authority on Windows systems. He writes:

Most people I know use registry cleaners as part of their magic cleanup routine, and I see very little upside and a lot of potential downside in this sort of routine use. Specifically, as I write below, I have never seen any evidence that routine cleaning of the registry has any positive effect. I stand behind that statement.

Another Windows expert is Microsoft Technical Fellow, Mark Russinovich, who also sees little use for Registry cleaners. He once said in his blog, "I haven't and never will implement a Registry cleaner since it's of little practical use on anything other than Win2K terminal servers."

On the other hand, there are those who are advocates of Registry cleaning. Microsoft itself even has a page where regular Registry cleaning is recommended. However, the Microsoft page is primarily a pitch for Live OneCare.

Why this division of opinion? Let us look in more detail at the three ideas behind Registry cleaning that were listed in the section above to see why the case for Registry cleaning is not as convincing as it might seem.

  1. The central role of the Registry and the constant addition to it -- According to experts like Mark Russinovich, the mere size of the Registry is not a factor in modern systems since the Registry is scanned very rapidly. Broken references to files and DLL's left behind by poorly uninstalled programs can be a factor in slowing down a PC. However, as I mention below, it is my opinion that this problem is better dealt with by regular use of a good uninstaller. Still, poor program uninstallers are one reason why Registry cleaning may help in some cases.
  2. Windows Rot -- I do not personally believe that this is primarily a Registry problem. The most common reason for the decay of Windows performance is too many programs running in the background and other causes that are listed later on in this article.
  3. The anecdotal evidence that Registry cleaning helped in older versions of Windows -- The Windows Registry has evolved considerably and old experiences are not applicable. The more recent versions of Windows beginning with XP are NT based with considerable changes from Windows 9x. Windows Vista and Windows 7 Registries are even less susceptible to corruption than XP with added protective measures such as Registry virtualization.

What about all the claims on the Internet that Registry cleaning makes a system faster? With one exception, I have found no Web page or post with actual data to confirm the conclusion. Ed Bott wrote in his blog:

I did a Google search for "registry cleaner" performance tests, and got more than 25,000 hits. In the first 15 pages, however, there wasn't a single example of an actual performance test. Virtually all the results were from companies that make and sell this sort of utility, or from download sites that have affiliate agreements with these developers.

The one reference I found that actually contained some data was from Steve Bass who has a good article in PC World. He gives some support to the idea of Registry cleaning but with a lot of reservations. He writes:

The big question is whether a Registry cleaner will speed up your PC, making it boot more quickly and run faster. The answer? I can say, emphatically and unequivocally, uh, maybe.

My own experience with Registry cleaners dates back to Windows 95. Back then I was a definite supporter of Registry cleaning as a a regular part of maintaining a system. It was my experience that performance was noticeably helped in Windows 95 and 98 systems. However, with the advent of Windows XP my opinion changed. I found XP to be much more stable. I ran an XP laptop for almost five years without ever feeling the need to clean the Registry. An XP desktop that received heavy use with much installing and uninstalling of programs did seem to slow down after three years or so and I tried a Registry cleaning with some marginal improvement in performance. Another XP system runs just fine after three years without having touched the Registry. Of course, these systems are regularly maintained in other ways. I have not seen any point in cleaning the Registry on my Vista system.

At best, Registry cleaning is an adjunct to other types of system maintenance and by itself will not cure sources of decreased computer performance such as these:

The basic conclusion that I come to about Registry cleaning is that it is a specialized form of system maintenance that only applies to certain patterns of heavy usage or badly corrupted systems. And that brings us to the subject of the next section.

Who Should Use Registry Cleaners?

Combining my own experience with the information on the Web, it is my opinion that the average PC user should not use Registry cleaners. Here are some reasons:

  1. The biggest source of Registry problems is usually remnants of programs that have been installed and uninstalled. Most average PC users do not engage in installing and uninstalling a lot of programs but if they do, regular use of a good uninstaller program is preferable to cleaning up afterwards.
  2. Registry cleaning can be dangerous without taking proper care. Most average PC users do not have the background knowledge to use a Registry cleaner safely. It is very easy to "clean" some Registry entry that should not be removed. I see too many posts on the Internet about Registry cleaning gone awry. Even highly rated programs that I have tried have offered to clean something that I knew should not be touched.
  3. In NT based versions of Windows, Registry cleaning is generally a marginal way to improve performance.This is especially true for Windows Vista and 7.

So who should use Registry cleaners? Here are some possibilities:

Using Registry Cleaners

There are many Registry cleaners available, both free and commercial. Most are part of a a software package for general system maintenance. One of these packages is the freeware program CCleaner , which receives numerous good recommendations. Here are some steps for those who do choose to use a Registry cleaner:

  1. Always make a system restore point first.
  2. If provided, also make sure the program makes a backup.
  3. Use a custom setting and not the default setting.
  4. Monitor all proposed deletions carefully. The programs sometimes wish to clean items that should be left alone.
  5. Have as few programs as possible running during the cleaning process.
  6. Do not use the computer during the cleaning.
  7. Reboot the computer to allow the changes to take place and check that the system is behaving properly.
