100% CPU on plugged in laptop

[Joe]

Yeah. When I plug in my laptop it uses 100% CPU, bringing everything to a halt. Unplug it and bam, fine. What gives?

This is also interesting because it's dual-core. That'd mean a single thread can only use 50% CPU, which I've seen many times. Wtfux?

[iago]

I guess one question is, which operating system are you using?

[Joe]

Windows Vista.

Also, this apparently only happens while plugged in and NOT charging. :-\

[Joe]

It was a feature of Vista Battery Saver gone awry. I uninstalled it since it didn't do much anyhow.