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If you've recently moved to a high-speed Internet connection, you're undoubtedly finding new and frivolous ways to put the additional speed to work. Downloading digital movies, streaming the BBC World Service, or listening to Radio Estonia are just a few examples. But as the novelty wears off, one question inevitably arises: Can I make it go even faster?

Sure, you can download a 400MB file over a cable modem connection in less than an hour, but if it took only half as long, you'd have yet more time to download other stuff that you'll probably never get around to using. It's likely you can squeeze more performance--maybe a lot more--out of your high-speed link with just a few clicks of your mouse.

Many Web sites offer to tell you your connection speed, but the tests they use aren't always accurate. Microsoft's MSN Computing Central Bandwidth Speed Test and DSL Reports' speed-test page gauge your download and upload speeds by timing the transfer of a small file to and from your computer. While this technique provides a general speed readout, the results can fluctuate dramatically. You're testing the speed of the entire connection between your PC and the test site's server, and neither you nor the Web site has any control over the efficiency of the routers in between. Also, testing a small file can lead to inaccurate results, and if that file is stored in your browser's cache, the results will be muddled further. Over several minutes, MSN clocked my cable modem connection at anywhere from 850 to 1250 kbps. While DSL Reports indicated steadier speeds in the vicinity of 950 kbps, there's no assurance that either service is accurate.

To get a more exact measurement of your connection speed, transfer a large, noncompressible file, such as a multimegabyte .mp3 or .zip archive file, between your hard disk and any nearby server that you have access to. The home directory that your ISP provides, an office computer, or a nearby FTP server are all good choices. Download and upload the file four or five times, and track how long each transfer takes. To find your connection speed in kilobits per second, convert the file size to kilobits by multiplying the number of kilobytes by 8, then divide by the transfer time. We'll use an 8MB file as an example. A megabyte is 1024 kilobytes, so our 8MB file is 8 times 1024 times 8, or 65,536 kilobits. If the 8MB file takes 1 minute and 40 seconds to download (100 seconds), divide 65,536 by 100 to get the per-second transfer speed. In our example, the connection is running at approximately 655 kbps. Try the tests at different times of the day to detect speed troughs. The wee, wee hours of the morning will likely be fastest, and weekday early evenings the slowest.

If that's too much math, let your browser do the gauging for you. Both Internet Explorer and Netscape Navigator do a pretty good job of tracking download speeds, which their download dialog boxes report in kilobytes per second. A 120-kilobytes-per-second transfer speed translates to 960 kbps. That's decent cable modem performance, but something tells me I could do better.