Obviously, we couldn't use pristine PCs to test the utilities, since they wouldn't have any crud to clean. So we collected five systems of different ages that had one thing in common: wear and tear. The test PCs were a Dell Latitude D520 laptop (1.66GHz Core Duo T2300, 512MB RAM, Windows XP Professional 32-bit), a Dell Inspiron E1505 laptop (1.6GHz Core Duo T2050, 1GB RAM, Windows Vista Home Premium 32-bit), a Lenovo ThinkPad Edge laptop (1.3GHz Core 2 Duo U7300, 4GB RAM, Windows 7 Professional 32-bit), a Toshiba Satellite M645-S4055 laptop (2.4GHz Core i5-M450, 4GB RAM, Windows 7 Home Premium 64-bit), and a custom-built desktop that we frequently use in the Labs (2.4GHz Athlon 64 4000+, 3GB RAM, Windows XP Professional 32-bit). Each of these five PCs had endured months, if not years, of frequent usage without even a light dusting, much less a comprehensive system scrubbing or Windows reinstall. In short, they were exactly the kind of PCs that most people would want to run a cleanup utility on.
First, Tony Leung and William Wang of the PCWorld Labs preserved each computer's precleanup state as a disk image; then, they ran WorldBench 6 on the systems in the precleanup state to obtain a baseline performance score.
Next, on each computer, they ran one of the cleanup utilities through its standard functions three times, to make sure that it didn't miss anything. They didn't uninstall any applications, even if the utility recommended doing so. (Getting rid of software that you no longer need is a good way to speed up a PC, but we wanted to see whether the other functions performed by each cleanup utility would make a difference with the same software lineup.) Afterward, they ran WorldBench 6 again to determine whether performance had improved. Then they restored the system to its original, cluttered state and started the process over with another cleanup utility.
Note: The testing process took weeks. All of the cleanup utilities we evaluated for this roundup have since been updated, so it's possible that retesting with the current versions of the programs would yield slightly different results.
WorldBench 6 Performance Results
While specific WorldBench 6 results varied from system to system, a clear trend emerged--namely, the cleanup utilities failed to help our systems' performance significantly, and in some cases they even made PCs ever-so-slightly slower. (Click the chart below to see it at full size.)