When designing a webpage, my computer used to freeze. When I checked the Task Manager, the CPU Usage reached to 100% wherein 98% is used by iexplorer.exe. I have been testing one of the webpage in Internet Explorer 6, 7 & 8 and each one of them made the CPU Usage reached to 100%. Using Firefox alone had no effect - meaning, it had its normal CPU Usage while testing the webpage.

I checked my CSS and tried to delete some of the codes until I finally saw this code which uses all of my CPU resources:

#content { height: expression(document.getElementById("content").offsetHeight); }

That is the code for IE6 to compensate its inability to interpret top:0; and bottom:0;