The need for speed

Computer shoppers often think that processor speed is the most important factor in performance, so they put their money on the fastest CPU they can afford. That's not always the best move, because a less expensive, midrange processor may actually perform almost as well and offer longer battery life than a faster, power-hungry CPU. In our tests, we used two Intel Pentium M processors.* The 1.73GHz Pentium M trailed the 2.13GHz Pentium M by just 7 percent but cost about $300 less and offered 22 more minutes of battery life.

For many types of users, putting money toward more memory (a.k.a. RAM) is the best strategy for boosting speed without giving up battery life. The more RAM you have, the more data your laptop can process without sneaking out to use the hard drive as a virtual memory cache. On average, it costs between $50 and $100 to bump your laptop's RAM from 512MB to 1GB; meanwhile, to go from a low-end CPU to a top-of-the-line one can run you from $300 to $500 or more. Doubling our test unit's RAM from 512MB to 1GB boosted its performance by 13 percent and cut only 8 minutes of its battery life. Beware of diminishing returns, however. Packing your laptop with more than 1GB of RAM won't yield vastly better performance unless you're a hard-core gamer or you work with demanding mathematical programs or advanced graphics applications.

Getting the right hard drive is also important, and a 5,400rpm drive can deliver a significant performance boost over a sluggish 4,200rpm model. One of the few mechanical devices in a laptop, a hard drive stores data in tiny magnetic marks on a rotating disc. The faster the disc spins, the faster the data can be read or written. If the disc can't keep up with the processor and memory, you'll end up waiting. When we replaced our test unit's default 4,200rpm drive with a 5,400rpm model--a $25 upgrade--we saw a performance gain of 18 percent and only 7 minutes less of battery life.

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