CPU time measurements, especially percentages, get very fuzzy when the CPU isn't loaded.

I'm on Chromium 12 on a Fedora 15 box. Top reports ~25% (on a dual core Arrandale, so that's about 1/8th the available CPU time), but checking the clocks more carefully shows that they're spending half their time in sleep states and never moving from the 1.2GHz base speed (this model turbos at 2.9GHz). So my envelope tells me this is about 4-5% usage vs. a fully loaded system.