After reading about the blazing fast boot time of Ubuntu 9.04 on Matt Cutts' blog, I decided it was worthwhile to go for the upgrade on my MSI Wind U100-432US. Before the upgrade I made sure to install bootchart and manually measure the boot time as well.
My measured boot times are from the GRUB boot menu to the GDM login screen. I pressed the arrow key at the boot menu to stop the countdown and then pressed Enter on the keyboard at the same time as starting the clock. All times were measured with the computer on AC power.
On Intrepid, bootchart showed a boot time of 36 seconds. My real time measurement was 50 seconds.
After updating to Jaunty, bootchart showed a boot time of 23 seconds and a real time measurement of 34 seconds. That's a real time improvement of 32 percent!
Here are the bootchart images for reference.