How much difference does fragmentation make?


Essential Member
Microsoft Community Contributor

I know that fragmentation makes a lot of difference.

I've had times when the difference between having fragmented files vs un-fragmented files would determine whether some processes would complete or not when generating 3D video.

If the files were fragmented it would just hang up after a while.
Defragment them and they zip right to the end.

But my computer has felt logy lately, and I haven't done a full defragment in a long time.

I looked at my C:\ drive and it showed as 11% fragmented.

Defragler now has an app that runs a disk transfer test on a drive.

So I ran the test several times and got a transfer rate of under 3 Mbs, really slow.

Then I did a full defragmentation, and ran the test again, this time I got 30 Mbs, a big improvement.

I can feel the difference when I do things on my computer now too, it just feels better.

Now it's working on my D:\ drive, it's been at it for hours but it has the backup of my C:\ drive on it too.

Anyway if the tests are correct then it's a numerical indicator of how much keeping your computer defraged can help, and that's only 11%, I've seen people how have hard drives are at 40%.



Microsoft MVP
Staff member
Premium Supporter
Microsoft MVP
Depending on use and level of fragmentation different users will have different experiences. People using software with low levels of disk operations will not see any effect from quite high levels of fragmentation whereas software with intensive disk transfers will perform badly with quite low levels of fragmentation. In either event it is good practice to keep defragged if only to save the drive getting thrashed. In the case of very large drives with high levels of fragmentation I have found it can be more effective to make a complete backup copy of the drive to an external device then copy it back completely to a reformatted drive - data security and efficiency at a stroke!

I won't quote that entire post, but I certainly agree with the last sentence.
It's how I've done HD defrags since long before MS wrote the first Defrag for Windows.

Back in the DOS days, the PCTools suite had a routine called "Compress" which was a defragmenter that looked exactly like what finally came out from MS. It showed the little boxes of data and moved them around to remove fragmentation and fill in empty spaces in the data pattern. If you ever saw the defrag in Windows 98, it was just like that.
But that was Pre-Windows, circa 1990.

I defragmented the main HD on an old Mainframe computer when I worked for the county. We were daily getting complaints from the users that the system was running SO SLOW. I backed up the entire drive to tape and then did a rull Restore. The next morning I got a call from the Head of the users and she wanted to know what I'd done, , , because the system was running SO FAST.

MS knew this when they first wrote Windows, that's why they added the Defrag program to the maintenance programs that come with Windows.
Disk Cleanup is another program that should be run on at least a weekly (not weakly) basis. It's even more effective if run in the "Extended Mode".
Here's the desktop shortcut for that.
%SystemRoot%\System32\Cmd.exe /c Cleanmgr /sageset:65535 & Cleanmgr /sagerun:65535

On first run, you have to check the little box next to each item that you want cleaned. DO NOT put a check next to
Office Setup Files or Setup.log Files. Leave those unchecked, but you can check everything else.

Cheers Mates!
O.T. :cool:


Windows Forum Admin
Staff member
Premium Supporter
When measuring the effect of fragmentation, the size of the disk is actually quite important. Fragmentation seems to have a cumulative effect on smaller, frequently used drives that lack a substantial amount of free disk space. That is to say, that on smaller drives, the problem of disk fragmentation being more pronounced and noticeable, to the point that such fragmentation produces an immediately noticeable lag or slowdown, is much more likely on these devices. FAT32 vs. NTFS resulted in much more file system efficiency and reduced a great number of problems associated with disk fragmentation. With larger drives, the problem of fragmentation begins to get more trivial, as the amount of allocated free space can often times make up for the number of frequently occurring file fragments.

Joe S

Excellent Member
Wouldn't the use of the drive or partition also have some impact too? A drive with OS and software would seem to me to be more fragmented than one just containing data.

Just quick comment... 'we' think about things, such as Defrag, in a certain light, w/ certain reasons & factors coming into play. And there is the oft mythical view or understanding of many End Users. WE know defragging on a regular basis is smart (ie in Win7, it's auto wkly, by default) AND WE know a drive needs a certain amount of free space to be able to preform this function. Anyway, he's my point:

1. End Users that think they should defrag but, have too much Used Space on their drive(s).
2. (here's the biggie) End Users I've many times heard say, "Dunno why it (their computer) is like that, I just defragged." OR "Should I defrag? Will that fix it? (it being whatever the problem in the machine might be @ the time)

In other words, the misconception floating around amongst them that Defrag is some sort of silver bullet, miracle instant cure-all.

Certainly it helps things but, it's kinda sad that 'they' have come to think it fixes things. They usually don't realise or arn't aware that what is more or additionally needed is to free up space, do Disc Clean-up, look for & remove malware, have & USE Ccleaner & all that sort of thing that WE take for granted. Yep, there is virue & value in defraging but, it's too bad so many End Users have come to think (not sure where they got it) that they can put all their eggs in that 1 basket.



Windows Forum Admin
Staff member
Premium Supporter
Because more files are being deleted, I would say that this is definitely the case. However, I think whereas you would notice a big time slowdown, this still takes 30-40% fragmentation, and I have seen some drives over the years that were heavily fragmented. This almost always happened when there was a severe lack of storage.


Essential Member
Microsoft Community Contributor

I removed my backup of C:\ from drive D:\ and then defraged it again.
I got noticeably better performance, it's like having that huge fragmented file in the middle of the drive was an anchor.

That also freed up half of the used space.

The transfer test now shows more like 60 Mbs for the drive.
This is up from about 6 to start with.

So from now on I'll keep my backups on my external drives.

I have also noticed that if I have all my external drives turned on (I have 4, 2 USB and 2 Firewire) I can see a real hit in performance.
This isn't a real problem since I never actually turn them on unless I'm using them, which means they are off 99.9% of the time.


Did I put anything in this thread that's visible?


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