Boot chart (www.bootchart.org), by Ziga Mahkovec, is an impressive and useful utility that monitors the boot process, creating data files that it uses to generate a graphical representation of your system’s boot process.
Boot chart isn’t installed by default on Ubuntu systems, but you can install it manually using either the Synaptic Package Manager or the apt-get utility. When installed on Ubuntu systems, Boot chart adds itself to the initial RAM filesystem used by your kernel to capture data about the boot process, and then adds a script to your runtime root filesystem’s startup process (/etc/init.d/stop-bootchart, symlinked to /etc/rc2.d/S99stop-bootchart) that processes the collected data and generates the graphical record of the boot/startup process.
Boot chart uses a Java application to generate a Portable Network Graphics (PNG) graphics file in /var/log/bootchart. This file is named based on the day that it was created and a version number; so that multiple files created on the same day don’t overwrite each other. You can configure Boot chart to produce graphics in SVG or EPS formats (or to preserve the data files that it creates) by modifying the /etc/init.d/stop-bootchart script.
Not only is it really cool to have a graphical record of the boot process, but that graphical record can becvery valuable in terms of helping you identify startup scripts that are running that you don’t want or need to run, extra invocations of system or X Window system processes, and so on. Boot chart adds very little overhead to your system’s startup process, but the view of the system startup process that it provides can be invaluable.
On Linux distributions that do not yet use an initial RAM filesystem (but still use an initial RAM disk), you can still use Boot chart by installing it on your system and modifying the GRUB boot entry for your kernel to include an init=/sbin/bootchartd entry so that the system runs the Bootchart data collection script before starting the /sbin/init program and executing the normal sequence of startup scripts.
>>> Read more about Optimizing the Ubuntu Boot Process <<<
Source of Information : Ubuntu Linux - Bible