OnSpeed does just one thing: it speeds up your Internet connection. It claims to give a speed increase of up to 10x for a dial-up connection and up to 5x for a broadband one. It does this by selectively compressing the different types of information typically downloaded when surfing. It uses different algorithms for compressing text, pictures, animations and documents such as Word files.

There are things OnSpeed 5.0 won't accelerate, the most important of which is file downloads. If you download shareware or PDFs, you'll see very little difference in speed, because these types of file are already compressed with efficient algorithms.

You can download the application directly from OnSpeed's site, though our copy was supplied by Avanquest, from whom it's also available. During installation, it required a Windows restart, then an update and another restart and finally a registration... and another restart. Once all this is completed, an extra toolbar appears in your browser: the program supports Internet Explorer, Firefox, Netscape, Opera and several others. The toolbar includes a Yahoo! Search engine, which is installed without asking.

You don't need to do anything to benefit from OnSpeed, which just sits in the background and gets on with its compression. A series of controls enables you to set the level of compression to improve speed, at the cost of image quality, and to customise several other parameters.

We tried timing the download of the front page of the BBC site on a 512kbps ADSL link, after having flushed temporary Internet files to clear the caches, and saw 4.2 seconds without OnSpeed and 2.7 seconds with it. The OnSpeed meter showed a speed increase of 2x for this, which is only a little optimistic. Downloading a copy of Firefox or a Word template showed no difference and the same meter, surprisingly honestly, showed 0x.

OnSpeed provides a statistics screen which breaks down your usage, so you can see the savings it's produced. From this, after an extended session visiting several sites and downloading several types of file, it showed an overall speed increase of 4.83x; a good figure. The increase in graphics download speed was 4.63x, the text speed increase was 7.34x and the upload increase for sending files - including e-mails - up to the Internet, was 6.67x. A cost of £25 per year for this kind of increase seems very reasonable.

In order to compress content before delivering it to you, the data has to first be transferred to OnSpeed's servers. Both transfer and compression take a finite time and can be affected by the number of people using the service at any time. We found some delays before data downloads started, though the overall download times were very similar with and without the accelerator.

The speed increases OnSpeed can provide obviously depend on the kind of browsing you do and the Internet connection you have. If you visit a lot of wordy sites or send out detailed e-mails on a dial-up link, you should benefit considerably. With a different usage pattern and a faster ADSL connection, it may not be so helpful.