Thanks for the idea. I just created a list of built-in apps, set them to point to some deafults that do not depened on the network performance (for instance, Calendar only includes Holidays, and displays year view), rebooted and measured time to start them in a succession. Apps that depends on internet are excluded.
While this is not super accurate because OS and app updates could affect their startup time, it is still something measurable. It will be interesting to see if a year from now a set of same apps with basically same functionality will take more time to start on the same (or newer) hardware.