I've been enjoying a fast and minimalistic browsing experience with Google Chrome for about a week now, and I'm not switching back to IE7, which I admittedly have been using before. Why I'm not using Firefox could be that I've never got dependent on plugins, and the experience with Firefox is somewhat bloated and unpolished in my opinion.
Anyhow, when I first tried Google Chrome I was bothered by occasional periods of high disk and CPU activity, which could last for minutes, or at least it felt like that. Since my hard disk is very loud when reading and writing, it really was bothering. Also the CPU activity was high at those occasions, which raised the CPU temperature, causing the CPU fan to spin, contributing significantly to the noise. This was a real showstopper for me, which felt a bit sad, since I had otherwise enjoyed the experience with Chrome.
Fortunately, after poking around the limited options settings in Chrome, I found a solution: Disable the "Enable phishing and malware protection" option, which is found under the Security section of the "Under the Hood" tab. This solved the problem completely, and Chrome is now very light on CPU and Disk usage. Total CPU usage for a days worth of work only amounts to a few minutes, which is very satisfying.
Of course, disabling a security feature is at your own risk. But in my case it was a matter of being able to use Google Chrome at all.