(FORTUNE Small Business) – Think before you ask Dave Chamberlain, "How's business?" The vice president of technology for the Web financial site GetSmart.com is liable to tell you down to the second how long it's taking customers in Chicago to open his site's home page and why visitors to competing sites are caught in an electronic traffic jam.

Chamberlain subscribes to a live testing service that for $1,600 a month evaluates his Website's performance in ten U.S. cities and tells him how fast his site and those of his competitors run. "The test results give me a solid idea of what our site looks like from the outside," he says. "Through the course of the day I can see if there is any significant change in download times. If there is, I can drill down to see if a particular backbone link is shot or if there's a problem in our data center." This kind of live testing helps Chamberlain avoid performance problems before they become severe enough to drive customers away from his site.

A surfer's-eye view is essential to succeed in the Internet Age. E-businesses have only a brief time to turn online shoppers into online buyers. If an e-commerce site takes eight seconds or more to display a catalog page or accept an order, the shopper will likely look elsewhere for a speedier and less frustrating site, according to marketing consultancy Zona Research.

Testing your e-commerce site's performance involves three strategies to make sure you're ready for business: pre-crisis stress testing for the heaviest imaginable traffic you can expect; general tune-up services that ensure your site has a professional sheen; and live performance testing, which acts as something of a periodic pop quiz on your site's response time.

Until recently, small companies had little in the way of preventive maintenance tools to help them implement these strategies and adhere to the eight-second rule. The testing software that was available supported large corporations--with equally large wallets. Today most of the software for smaller companies can still run into the five figures, but there's a wide range of testing choices, from easy-to-use programs that run on in-house PCs to subscription testing services that pound your site with traffic from computers across the country or on the other side of the world. The performance reports you receive tell how shoppers are experiencing your site and how much traffic is too much for your e-business to bear.

Any sites that can expect to experience wild holiday and seasonal traffic spikes should consider the pre-crisis testing known as load balancing. These traffic simulations can show you how your Website will respond if hundreds, thousands, or even millions of e-customers arrive at the same time. Every site has a breaking point, and load tests will tell you where your site slows to a crawl or stops completely. If this point is within the range of what you can expect on your heaviest shopping day, it's time to add Web servers, faster database links, or additional network bandwidth.

Vendors of testing software include two longtime suppliers to corporate customers, Mercury Interactive (www.mercuryinteractive.com) and Rational Software (www.rational.com). Mercury's Astra LoadTest ($9,995) and Rational Software's Rational Suite PerformanceStudio ($15,000 to simulate hundreds of users) both let you create virtual shoppers and have them place orders, browse catalog pages, and check order status, not just log on to a home page.

Mercury also sells its high-end LoadRunner technology as a service. For $15,000, Mercury develops customer profiles, runs a test simulating 100 users, and retests to analyze the effects of any performance tuning.

Even if you build an industrial-strength Website ready for Amazon.com traffic levels, you're not immune from lost e-business. Other bugs, such as broken links that give customers error pages instead of the page they wanted or electronic shopping carts that don't reflect the latest pricing information, can also send shoppers away. "Last Christmas everyone was surprised because there were very few examples of sites crashing because of too much traffic," says Bill Thornburg, Rational's product director in the automated testing unit. "The bad news was that a lot of business transactions didn't work, so products didn't get shipped." Rational offers Rational Suite TestStudio ($7,295) to help e-tailers analyze the integrity of all the programming code that makes an e-commerce site work.

For larger-scale e-commerce sites, Rational's solution may make sense, but it's overkill on less complex undertakings. Sites that still want to guarantee a professional image can look to less expensive solutions, such as one offered by Web Site Garage (www.websitegarage.com). For $399 per Website, Web Site Garage tests your links and looks for spelling errors, checks for problems that may make your site look bad in Microsoft's or Netscape's browsers, and tests page-load time. It's a Web-based service, so no software is required.

The final aspect of performance testing to consider is live testing like what GetSmart.com uses from Keynote Systems (www.keynote.com). Companies subscribe to Keynote's services to see how fast pages load from customers throughout the country or the world by using actual PCs in 50 cities rather than computer simulations. The advantage is that the tests include the overhead of actual Internet backbones and network segments to show you why, say, London shoppers are hanging up while Parisians are frantically buying.

Even if Keynote customers don't have direct control over the problem--a broken network segment in Chicago, for example--the company can alert its network service provider instead of waiting for it to discover the emergency. "Keynote gives us a little heads up," Chamberlain says. The result: Web customers endure fewer performance frustrations.

Service plans vary from 100 locations and 50 cities throughout the world ($1,495 per month) to more modest local offerings. Small businesses with tight budgets, for example, can test from ten U.S. cities for a subscription of $295 per month.

An even less expensive alternative is SecretShopper, from WebPartner (www.webpartner.com). SecretShopper checks as many as five Web pages, on your site or a competitor's, for $179 a year. SecretShopper Checkout ($349 a year) tests three checkout processes of ten pages or less. Both SecretShopper options test your site every 15 minutes, send you alerts by e-mail or pager when there's a problem, let you monitor results in real time, and can be upgraded to view more pages. The primary difference between WebPartner and Keynote is that WebPartner is testing from just one locale on the East Coast and one on the West Coast.

None of the options is cheap, but then none is as costly as a customer who leaves your site believing you're not ready to do business.