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@defa85 My first step was to divide the boot time into two sections. 1) System is up. 2) Network is functional.
If you start with section 1, issue the command service network disable and reboot (make sure you have a serial/usb connection). The system will start without loading the network, I expect this will be around 30 seconds.
Depending on what services and kernel modules you load, you may be able to tweak this a bit by disabling a service and loading it after your app, or removing kernel modules you don't need. We're talking a second or less for most of this standard stuff.
Network connection accounts for roughly 50% of the entire boot process so if you can optimise this you will notice an impact. An ethernet connection is faster and while you may think a static IP is faster, that is not necessarily the case on all routers. Disable ipv6, configure a specific channel if you are using wifi.
dmesg will give you the timings, but for more detail you can enable more detailed debugging during boot up by watching for this prompt:
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
press 4 and enter, then once boot is complete use the dmesg command to see the details and timing.