Scott began analyzing the X Server patch-set for Moblin, that included enabling UXA acceleration by default, avoiding duplicated saved hardware states, reducing the driver boot-time, and disabling other operations. However, Ubuntu already incorporated all of these patches besides using UXA acceleration. Ubuntu's X Server also has a few extra patches, but those didn't seem to impact the performance.
After that, Scott came to no conclusions, but has now thrown the ropes to the principal X maintainer at Canonical (Bryce Harrington) and their technical leader (Matt Zimmerman). His mailing list message with Bootchart results can be found on ubuntu-devel. Hopefully by Ubuntu 9.10 (the Karmic Koala) we will see an X Server start-up time closer to Moblin, but that means cutting the time in at least half. Beyond just the X Server being speedier, Moblin V2 Core Alpha boots super fast.
Remnant is also looking at sreadahead vs. readahead performance for improving Ubuntu's boot performance.