Question: What are your tips for improving overall system performance on ubuntu? Inspired by this [question](https://askubuntu.com/q/2099) I realized that some default settings may be rather conservative on Ubuntu and that it's possible to tweak it with little or no risk if you wish to make it faster.

This is not meant to be application specific (e.g. make firefox load pages faster), but system wide.

Preferably 1 tip per answer, with enough detail for people to implement it.

A couple of mine would be:

* Install [Preload](http://techthrob.com/2009/03/02/drastically-speed-up-your-linux-system-with-preload/) (via Software Center or `sudo apt-get install preload`);
* Change [Swappiness](https://help.ubuntu.com/community/SwapFaq) value - "which controls the degree to which the kernel prefers to swap when it tries to free memory";

What are yours?

PS: Since this is not intended to have a unique answer but rather, several useful tips, I'm making this community wiki out-of-the-box.

Answer: 
Set `vm.swappiness=10` in `/etc/sysctl.conf`. I get a noticeable speed improvement when I fill memory. Since I use Eclipse most of the time, physical memory can become a sparse commodity.

EDIT:

From the [Ubuntu Swap FAQ](https://help.ubuntu.com/community/SwapFaq#What%20is%20swappiness%20and%20how%20do%20I%20change%20it?):

"The default setting in Ubuntu is swappiness=60. Reducing the default value of swappiness will probably improve overall performance for a typical Ubuntu desktop installation. **A value of swappiness=10 is recommended**, but feel free to experiment. Note: Ubuntu server installations have different performance requirements to desktop systems, and the default value of 60 is likely more suitable."

The FAQ is pretty complete about explaining what swap is, how it is used and how to change it. Recommended reading for anyone thinking of tinkering with swappiness or the size of swap file on disk.
Close applications that are not used all the time.

A lot of standard applications use a lot of memory and often also CPU while they are running in the background. Webbrowser, email clients etc are very inefficient in memory usage and the javascripts embedded often use CPU time with no benefit to the user.

Just by only running the applications that are used currently, the system will be a lot faster. Also, stopping applications is the only way of freeing memory lost in memory leaks.

The startup of the application on a fast running system is often less than switching windows on an overloaded and slow system.