Will setting up dual monitors on a decent-but-not-too-powerful machine significantly slow down my system?

For specifics to my system, this is a 2GHz Intel Dual-core laptop with 4GB RAM and a decent integrated video card, has no problems running multiple applications with Compiz and effects.

The monitors in question are integrated 1366x768 laptop screen and external 1200x800 monitor, nothing fancy or outrageous.

So, in your experience / knowledge, will running dual-monitors significantly detriment operation speed?

  • Please add what kind of video hardware you have. Oct 15 '10 at 18:14
  • Would, but I actually don't know how to determine the capabilities of the chipset. lspci gave me a generic model name, not a specific number, so was unable to look this up.
    – emf
    Oct 17 '10 at 17:20

There's more to render so sure, a little bit more of your CPU and a little bit more of your graphics are going towards keeping the system running. But we're only talking about a couple of CPU seconds extra per minute. Nothing that you'll notice.

If you run 3D things (eg games or other rendering things) over both screens, you will notice a large slowdown because you're dealing with twice the resolution and they're already CPU/GFX intensive. But if you limit them to one screen (like a window that is "fullscreen" on one monitor), you won't see much of a slowdown at all.

Either way, having the extra screen will near-double your own performance so that should easily offset any slowdowns.

  • 1
    Not sure about ~=2x performance increase. I find that for a daily programming, a dual monitor setup actually lessens productivity; instead, a single monitor with a good resolution, say WUXGA (of my laptop), tends to be more optimal. It depends on the use, of course.
    – Gödel
    Oct 15 '10 at 18:54
  • 3
    I know from a webdev perspective, having three windows fighting for the foreground (editor, console and browser), I really appreciate the extra screen space. But two 1920*1200 screens certainly takes some getting used to.
    – Oli
    Oct 15 '10 at 19:23

My processor's fairly old in terms of memory and processor speed my system's similar to yours (though it's not a laptop) and I use dual monitors perfectly fine. One running at 1280*1024 and another at 1440*900.

Just a setup I've accumulated over the years but I find it handy.

For general desktop use it's fine, but I've never had any heavy dual monitor 3D rendering on the go (not across both anyway) though in windows I do find that because I'm only using one monitor for games the other monitor is still rendering the desktop, so when the wallpaper updates the system slows down for a few seconds... not sure wether this would still occur in a single monitor setup or not!

Knowing windows it'd probably still swap the new wallpaper into memory even if you weren't using it!


I would think the performance cost would be minimal and if the video card is decent like you say and the system has a decent bus speed I don't think it would an issue.

  • 1
    Thank you. How do I determine bus speed, if you happen to know?
    – emf
    Oct 15 '10 at 18:09

You should check your laptop's video details before purchasing the second monitor. For some older laptops, the highest resolution they can produce is still not enough to the desktop of two monitors. I used a older Lenovo R51 and running 1024x768 on the laptop plus 1280x720 on an external monitor was too much. I had to choose either the laptop or the monitor but not both.

As for making the system slower, I have not experienced any major differences in performance. If you are running a 3D enabled desktop then there's more resolution to cover. In gaming, you would most likely only play on one monitor, so the performance should be the same as using a single monitor setup. I have noticed that some games run worse with two monitors and sometimes it's needed to run a game in a "windowed" mode.


With a system like yours there is very little chance you will notice much slowdown, in fact I would imagine there won't be many times such a slowdown would be noticeable.

The part of your system that would be very slightly taxed would be your graphics card, but if you're not an avid gamer then you're unlikely to notice.


I've been running this setup for a while now. On recent releases of Ubuntu I've had dual screen working with Intel, Nvidia and ATI graphics. I would recommend installing the proprietary drivers for these as well.

Internally you will create a big screen 2566x800 which will handle the dual screen's, I expect that your hardware will be able to do this. Because most of the work is done on the graphics chipset side I wouldn't expect to see any detectable slowdown in normal operations.


The issue that i see on my 2008 Mac Mini (which i use with Logic pro X for music creation, and VideoPad for video creation and editing is not an issue with computational degradation per say, but rather a significant degradation in system responsiveness. The reason for this in my case is due to the system design utilizing integrated graphics controller which shares its framebuffer memory out of the CPU's system memory. The results in twice the amount of ongoing contention between the GC amd the CPU for system memory access. Thiis additional memory contention leads to real time deadlines being broken for apps like the ones i mention resulting (in the Logic Pro X app for example ), in glitchy audio rendering, system overload errors and other real time perceivable artifacts. Note that if you are using an add-in graphics card solution with its own private graphics memory you won't have these same real time responsiveness isses with the second monitor.

Cheers, Gary Solomon Retired Chief I/O Architect PC Client Group Intel Corp.

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