I had not heard of this phenomenon before, but it is being reported that Firefox is causing systems to run harder than other web browsers. This is allegedly due to web pages that have a lot of Flash-based content which makes the CPU run harder and longer. It seems the system heat goes up and causes the fans to go into overdrive to keep things cool.
This is not causing netbooks to melt, but it would certainly hit lower spec hardware harder than its bigger siblings. I will have to keep an eye out for this, or maybe an ear open for increased fan noise. How about it — have you noticed Firefox hitting your fan harder than Chrome, Safari or IE?