Introduction

This tutorial will show you how to make your raspberry pi 4 with Raspberry PI Os Lite boot faster

Check initial boot time

In order to know that our changes actually do something, we will check the boot time before we change anything In Raspberry Pi Os you can check the boot time with this command:

sudo systemd-analyze time
Startup finished in 2.241s (kernel) + 17.891s (userspace) = 20.132s
graphical.target reached after 17.853s in userspace

In my case stock Raspberry Pi Os Lite took ~20 seconds to boot
Thats way to long for my use case
Let's fix it

Disable waiting for network

The first tweak is to disable waiting for network on boot. This can be done through raspi-config.
sudo raspi-config
This will bring up a. Follow this path to disable:
System Options -> Network at Boot -> No -> Ok

Disable services

The next tweak is disabling not needed services
Raspberry PI Os comes with a handy command which prints a list of all services sorted by start time

sudo systemd-analyze blame
12.004s dhcpcd.service
7.085s hciuart.service
3.680s console-setup.service
2.767s dev-mmcblk0p2.device
1.655s raspi-config.service
923ms rpi-eeprom-update.service
566ms systemd-udev-trigger.service
530ms dphys-swapfile.service
519ms keyboard-setup.service
515ms avahi-daemon.service
481ms systemd-logind.service
447ms networking.service
399ms systemd-fsck@dev-disk-by\x2dpartuuid-edb23c1b\x2d01.service
359ms systemd-timesyncd.service
317ms rng-tools.service
...

Warning: you cant disable all services because some of them are actually needed
Here is a list of services which are safe to disable below:

sudo systemctl disable ntp.service
sudo systemctl disable rsyslog
sudo systemctl disable dphys-swapfile.service
sudo systemctl disable keyboard-setup.service
sudo systemctl disable systemd-journald
sudo systemctl disable systemd-timesyncd
sudo systemctl disable systemd-udev-trigger
sudo systemctl disable rpi-eeprom-update.service
sudo systemctl disable apt-daily.service
sudo systemctl disable wpa_supplicant
sudo systemctl disable wifi-country.service
sudo systemctl disable hciuart.service
sudo systemctl disable raspi-config.service
sudo systemctl disable avahi-daemon.service
sudo systemctl disable triggerhappy.service

If you need bluetooth dont disable hciuart.service

Config file

After that we have the config file
Here we will overclock the pi

sudo nano /boot/config.txt

And add the following

# overclock
over_voltage=2
arm_freq=1850
initial_turbo=40

My full config.txt looks like this (i deleted all the unnecessary comments etc.)

# display settings
hdmi_group=2
hdmi_mode=85
hdmi_force_hotplug=1

# general
dtoverlay=vc4-fkms-v3d,disable-bt
max_framebuffers=2
dtparam=audio=on

# overclock
over_voltage=2
arm_freq=1850
initial_turbo=40

Cmdline file

The last fix is the cmdline.txt file. Here we will disable the boot messages (yes, this takes time)

sudo nano /boot/cmdline.txt

And add "quiet" before rootwait Then your file should look like this
Warning: Do NOT copy&paste this because PARTUUID is always different

console=serial0,115200 console=tty1 root=PARTUUID=61dc8113-02 rootfstype=ext4 elevator=deadline fsck.repair=yes quiet rootwait

Result

Let's reboot the pi and check how much we could reduce the boot time

sudo systemd-analyze time
Startup finished in 1.116s (kernel) + 2.454s (userspace) = 3.571s
graphical.target reached after 2.422s in userspace

Amazing result. We got it down to just 3.5 seconds