Measuring boot performance in Ubunu is fairly simple. Systemd provides a tool for that.
The overall boot time for kernel and userspace is given by:
systemd-analyze
How much time each boot services takes in descending order is displayed as follows:
systemd-analyze blame
The critical chain for the default target is shown my this:
systemd-analyze critical-chain
Those time can also be graphed as svg:
systemd-analyze plot > boot_analysis.svg