Speed up Ubuntu

Swap

Swap uses the hard drive as RAM, which is slow. Most of todays computers have enough RAM:

sudo sysctl -w vm.swappiness=10

sudo gedit /etc/sysctl.conf

add:

vm.swappiness=10

Prelink

Prelink resolves addresses of shared libraries in advance this reduces number of relocations.
It will make faster startup times for commonly used programs:

sudo apt-get install prelink

sudo gedit /etc/default/prelink

Change PRELINKING=unknown to PRELINKING=yes

sudo /etc/cron.daily/prelink

Preload

Preload monitors files of frequently used applications and and loads them in to the memory when system is idle. This will also make faster startup for commonly used programs:

sudo apt-get install preload

Boot-Up Manager

This is an utility for managing startup scripts. Here you can remove things you don't need.
You can disable "saned" an API library for scanners if you feel you don't need it.

sudo apt-get install bum

You will find Boot-Up Manager here: System->Administration->Boot-Up Manager

Disable startup applications

System->Preferences->Startup Applications
Here you can disable applications you don't need. I disabled the Evolution Alarm Clock, since I never use Evolution and Remote Desktop.

Decrease your boot time with concurrency

sudo gedit /etc/init.d/rc

Change CONCURRENCY=none to CONCURRENCY=shell

Disable IPV6 to speed up Internet

sudo gedit /etc/modprobe.d/bad_list

add: alias net-pf-10 off Reboot. If this command is empty, you have disabled IPv6:

ip a | grep inet6

Speed up Firefox

In the address bar, write: about:config
Change network.http.pipelining to true
Change network.http.pipelining.maxrequests to 8
Change network.http.proxy.pipelining to true
Change network.dns.disableIPv6 to true
Change plugin.expose_full_path to true

Right click->New->Integer:
Name: nglayout.initialpaint.delay
Value: 0

Right click->New->Integer:
Name: content.notify.backoffcount
Value: 5

Right click->New->Integer
Name: ui.submenuDelay
Value: 0

Sources: http://ubuntuforums.org/showthread.php?t=140920
http://www.pelagodesign.com/blog/2009/07/21/how-to-make-ubuntu-linux-run-faster-on-a-laptop/
http://ubuntuforums.org/showthread.php?t=179540