Inspiron 1521 slows down until unplugged?

I have an inspiron 1521 that I got a few weeks ago.

I haven't done any troubleshooting yet, I figured I would

I'm using winamp, msn messenger, firefox, avast, and zonealarm.

While the computer is plugged into the wall (and on high performance power plan) after a while the whole computer will become very sluggish until I unplug the computer, at which point the speed returns to normal.

I was just wondering before doing troubleshooting if this is a known vista issue, dell issue, or even laptop issue.

I've mastered the desktop, but I'm still learning laptops.

Thanks

-Simba

Inspiron 1521 slows down until unplugged?norton 360

Never heard of this problem before but

Here are two things I can say :

The latest version of zone alarm will take a huge amount of memory to run. If you purchase zone alarm and have all the features, It will automatically check for spyware and do a virus scan once in a while. It might actually wait until you have plugged in your laptop to run the virus scan which would explain why your pc becomes slow.

Also, vista could turn into a better quality setting if you are plugged in and go to a lower setting if you unplug to make your battery last.