Time startup of different units
The code in this repo helps with timing and logging the startup of a linux distro. Type make to build and install the timing utility. This installs a /usr/local/bin/startup-log utility, which takes one argument and logs the current tsc value and the argument to /var/startup-log.
So you want to add the logging of every systemd service in the system as StartExecPost= argument. If you are brave run make enable. This will most probably destroy your system for good, and make your toaster explode. Better take a snapshot of your vm (you are running this in a VM, right?) before. But if you are lucky, the startup of every service will be timestamped and logged. Similarly make disable will remove the logging from every service file in your system (or maybe just trash all of them).