Interesting little bit of information I discovered yesterday about how IE manages memory usage. I was testing a site in IE & I needed another window open to view a different section on the site, so for some reason I clicked the icon rather than pressing ctrl-n. Later on I opened up Task Manager to kill a stalled program & I noticed that there were two instances of IEXPLORE.EXE listed. This, I thought, was odd. I’d always assumed IE spawned new windows off the same process instance, but it appeared not.

So then I go back into IE, press ctrl-n and check back on task manager and low & behold, there’s no new instance, just a memory use increase in one of the current ones. So it would seem that how you open IE changes how it manages the processes it uses. Here’s a shot of task manager with IE & Firefox both having the same four sites open, the 1st with the IE windows opened using ctrl-n and the other with them opened by clicking on the IE icon.

Single Process

Multiple Process

Each successive IE processes has less memory usage, so it would seem that it’s either caching or sharing some of the resources, but none the less, to open the same four pages, the memory usage difference is huge – 74,236KB! So the lesson for today is, use ctrl-n. (Well, actually, the lesson is use Firefox. Even with all the windows opened on the single process, Firefox still used less memory)