How to make a PC run faster is a question I often see in PC utility chat rooms. The responses vary from spyware as the culprit to just upping your CPU's power.

Of course, everyone wants a fast computer, but very few people ever give any consideration about what is making their system slow. Sure, spyware and viruses can have an adverse effect on system performance, but there are software packages you can buy that proactively keep these miscreant pieces of software away from your system.

The truth of the matter is that if all your hardware and software were operating properly your system will slow down with time and use anyway.

A common response to these system slowdowns is to buy a newer and "faster" system. But is this the sensible approach? The newer and faster way means getting a new rocket ship machine with a 3.0GHz Pentium 4 processor. If you're doing complex modeling, calculating the value of Pi to the nth place, or are a very high-end game user, you might need this CPU power.

If you are like the rest of us and writing e-mail, surfing the Internet, creating Word documents, spreadsheets, PowerPoint presentations, and doing some family photo swapping, most of the time your CPU sits idle waiting for the disk to deliver it some data.

Power, Speed, and Space

The number of transactions a silicon chip can process per second has grown exponentially and now measures in the billions per second. At the same time, the newer disk drives can move from one point on the disk another in about 10 milliseconds, which means processors can process data faster than disks can deliver it.

Every disk partition has a Master File Table (MFT), which is the index to that partition. The MFT contains all the information about the size and location of a file. When an application requests a file, the file system looks in the MFT for the files logical location. The starting point and length of the file is reported to the disk controller and the data is read from the disk. If the file is in one location, the file system can quickly report the one starting point and length and off you go.

But wait a minute; there is a phenomenon of the Windows file systems called fragmentation that causes files to be created in more than one piece. This happens when the file system cannot find enough contiguous free space to create the file in one segment. It is not uncommon for some frequently modified files to wind up in hundreds or thousands of fragments.

If the file you want to call up is in 500 pieces, the file system must report the starting location and length of every fragment to the disk controller. This takes time. For people accessing a file server, accessing a badly fragmented file may take several turns at the server just to read a file.

Instead of using your turn at the CPU to process data, you are wasting some turns by having to wait for the data to be read. This also happens on laptops and desktops. If you're running an application and have noticed the disk is busy, but nothing is happening on the monitor, you are probably waiting for the data to be read.

The disparity between CPU speed and disk speed, along with the implications of file and free space fragmentation, explains why systems slow down. As more files are added to a disk and fragmentation increases, it simply takes longer and longer to access a given file.

The time it takes for read and write access to the disk drive is the performance bottleneck on today's computers. The disparity between the electronic speed of processors, the electro-mechanical speed of disks, and the impact of file and free space fragmentation are the reasons good systems slow down.

Sounds complex, right?

To Defrag or Not to Defrag

You wouldn't drive your car without periodically taking it in for maintenance, so why would you run your PC without doing the common-sense things that ensure its performance?

Studies show that fragmentation can slow file access by up to 90 percent from when the PC was new. Disk defragmentation with the right tool can keep systems running at their optimum performance level.

The right defragmentation tool is one that defragments your files and also consolidates your free space. The defragmenter that comes with Windows only tries to defragment the files--and it does it in a very inefficient manner.

Gartner, the IT industry analyst group, issued a Research Note in which that noted, "The built-in defragmentation tool is a multi-pass defragmenter that must be run over and over to defragment the disk, especially when defragmenting very large disks with heavy fragmentation and limited free space. As such, multi-pass defragmenters characteristically fragment the remaining free space on the disk, which accelerates fragmentation later."

When your available free space is fragmented, the file system is more likely to create fragmented files right from the start. This means the time needed to access a file will be greater.

Ideally, you should access a file in a single physical disk seek; if it takes more than that, you are experiencing more disk seeks than are necessary. The result is longer time to both read from and write to a disk.

Unnecessary seeks to the disk waste time and resources, and fragmented free space increases the number of unnecessary seeks. On a 3GHz processor, a single excess disk seek of 10 milliseconds waste 30 million processor cycles.

What are the economic implications of not defragmenting? A recent study by a former Microsoft file system engineer shows that free space fragmentation can slow server read/write performance by up to 24 percent and workstation performance by up to 74 percent.

What impact would this slowness have on productivity at a typical business? Let's say a hypothetical company has 100 users who average four hours of system use a day, 240 days a year. Let's say the total company cost of an employee is $25 per hour, and defragmentation improved their system performance by a modest 10 percent.

The annual productivity savings? 100 x 4 x 240 x 0.10 = 9,600 hours. Times $25 equals $244,000.

This amounts to 96 hours per year per user (or 2.4 weeks a year) unnecessarily spent waiting for files to open. Keep in mind the average improvement is not 10 percent, but 30-50 percent.

This savings does not take into consideration reduced help-desk costs, since there were fewer reports of slow systems or application errors. Nor does it consider the deferred hardware cost saved because systems weren't unnecessarily replaced.

Keep Ahead of it

The technical press is filled with stories of spam and spyware, their adverse effects on system performance, and the dent they make in productivity. Many organizations are jumping to address these issues, but at the same time they overlook the obvious things they can do to make things run better.

Proactive disk defragmentation with free space consolidation will keep systems running better, and longer, with less maintenance and at a lower cost than just about anything else they can do.

Still not convinced? Read Balder Research's white paper "Impact of Free Space Consolidation on File System Performance."

Robert E. Nolan is president and CEO of Raxco Software (bobnol@raxco.com).