Compare to earlier ubuntu versions karmic is much better in speed but if you still want to reduce your boot times use ubuntu boot Packages containing instrumentation to aid in boot performance work, and packages proposed to improve performance.
Note:- Install these packages with your own risk and this might break your system
At the moment this packages are available to only ubuntu 9.10 (karmic) users
Install Ubuntu Boot in Karmic
First you need to run the following command from your terminal to add sources list
sudo add-apt-repository ppa:ubuntu-boot/ppa
Now update the source list
sudo apt-get update
Install using the following command
sudo sudo apt-get dist-upgrade
or you can install linux,ureadahead packages
This will install all the required packages.
I hope after installing this your boot times would be much faster.