Observations On Browser CPU Usage

Something I have been keeping tabs on lately is CPU usage among the two browsers I use: Firefox 3.6 and IE 8 running on Windows 7 Pro 64-bit. While you can find lots of information and benchmarks on the web regarding memory usage and Javascript performance, you see very little about CPU usage. One resource on the subject I found was this performance comparison which was interesting, but as you may know I do not give much weight to benchmark scores.

From my observations Firefox is considerably faster than IE 8 with regards to displaying pages (note, I do have NoScript running in Firefox so this most definitely contributes to this), however the CPU usage of IE is almost always lower. Firefox has a tendency to spike when only viewing HTML pages while IE typically never does this. If a page is using Flash, all bets are off.

Of course, if you load up Firefox with add-ons there is going to be some impact, but I only use 2 that impact page content: NoScript and Flashblock. So I can only conclude that Firefox takes a “greedy” approach to get what it needs done as fast a possible where IE is more “considerate” by using less CPU for a longer period of time. Of course, this is not a scientific or conclusive study it is interesting to see the two different approaches. Whether this behavior is by design or coincidence, who knows…

Granted, CPU usage is not nearly as critical as it used to be as most all systems today are multi-core, I still believe this is an important indicator to keep tabs on.

What observations have you noticed on the browser(s) you use with respect to CPU consumed? Does this even matter to you?


  1. Like you said, with regards to CPU usage, it's really not that important in the world of multi-core processors and hyperthreading. I do like knowing which programs are 'hogs' and which ones are 'lite' in regards to system resources, to determine which browser is best to use on my workstation, my home desktop, or my (older) laptop. I also like trying out new browsers to see if the latest and greatest is really bringing something to the table. When using my desktop, browser CPU usage isn't an issue, so I like using a fast browser, regardless of it being a 'hog'. I got used to using Safari and Opera, heavy, but fast browsers. However, I have reverted back to FF as my primary because even though it seems slower, FF isn't as buggy, and is more compatible with sites that are picky about which browsers work best. After trying to use government websites and working through glitches in the latest iteration of those browsers, I'm going to stick with FF for a while. Don't we all just want the fastest web-browsing possible, with minimal waiting, pop-ups, compatibility issues and the like?

  2. CPU usage is ALWAYS important. It may not be important to you if you have a newer PC, but it's still important. As a software developer, it irritates me the lack of concern for some things because “they're not important anymore”. — basically because developers are lazy — that result in software bloat, memory leaks, and inefficient code.

    Now that I've ranted, I think your observations are correct, even for the last few versions of IE/FireFox.

  3. A side note: Is using NoScript AND Flashblock not an overkill? Just wondering.

    • Actually it is not. I have NoScript set to allow Flash so it gets picked up by Flashblock.
      The reason I do this is Flashblock allows you to enable flash with a single click where NoScript requires you to first allow the page to display flash (via a dialog box) and then click another window to have Flash actually load. Overall this method works very well for me.

Speak Your Mind