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I just upgraded an old, secondary computer to the latest Kubuntu (10.10). It seems the effort was a bit too much for the hardware and one 512MB memory module died. I tried to take it away, clean the connectors, put it back several times, but to no avail.

Until such a time I can find a second hand DDR memory module, I am left with a meagre 256MB RAM, which is below the official requirements (384MB) to run Kubuntu/KDE. Indeed: the computer constantly swaps the memory, making everything painfully slow.

Since Kubuntu is already installed and I use it on all my computers (and I want to keep KDE for when I really need it), how can I configure ubuntu to squeeze out every bit of unnecessary memory usage?

This is a secondary computer but still very useful. We use it mostly for web browsing.

A "lightweight" tag is missing.

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up vote 8 down vote accepted

Kubuntu is really ubuntu with a KDE desktop instead of GNOME. The lightest I know of is lubuntu (lubuntu-dektop package) this is still running the same thing underneath Kubuntu and normal ubuntu just with a lighter desktop.

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+1 for Lubuntu. Even better than XFCE. If you do not feel for reïnstalling the desktop, install it by running sudo apt-get install lubuntu-desktop. – Lekensteyn Mar 4 '11 at 17:25
Thank you both. lubuntu-desktop comes with its own desktop manager, ldm, to replace kdm, which was another item I thought could be improved. – augustin Mar 6 '11 at 3:26

The first thing I did was install XFCE4 and use it as the default desktop environment, instead of KDE. This I know is the single most important step I could take. It already makes a huge difference. The system is responsive again.

Still, the memory usage (as indicated by free -mt) is very close to the limit of available RAM, and depending on browsing usage, some swapping may still occur.

Please share other tips in other replies.

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This is not really related to Kubuntu. You're essentially changing desktop products, not optimising KDE. – Oli Mar 4 '11 at 11:57
I never said I wanted to optimze KDE. I am still running Kubuntu, though. It didn't come with XFCE already installed. I had to install it and configure it. The question now is: what other default services and configurations (system wide) can I change to make Kubuntu even more like whatever light-weight distro their might be? – augustin Mar 4 '11 at 12:55

One thing that may help is setting up your swap partition for speed - with that little RAM, things will swap to disk and any RAM-based tasks become disk-limited. If possible, move your swap partition to a separate hard drive, and make sure it's reasonably large (3x your RAM is my usual rule of thumb).

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  1. Install openbox by typing sudo apt-get install openbox in the terminal.
  2. Log out and log in with openbox.
  3. Open the terminal and type plasma-desktop then press Enter and wait.
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