What are your tips for improving overall system performance on ubuntu? Inspired by this question 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 (via Software Center or sudo apt-get install preload);
• Change Swappiness 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.