Boot time is how much time it takes to boot your computer when you press your power button. A lot of things can slow down your boot on Linux. In this article we will discuss this in detail.
Systemd optimizations
Disabling unnecessary services
systemd-analyze is a command available on systemd distros (which most distros are). It shows which service is using more time to load and you can disable that service. Just don’t disable any important service or your computer won’t boot at all.
You can also use the sub-command systemd-analyze blame for more clearer output.
Using .socket instead of .service for starting service
.socket are used to initiate the service process when its needed while .service starts the process on boot which costs boot time and unnecessary for services like cups
Slimming Down initramfs
Mkinitcpio
Using Systemd instead of Busybox on early init
By default, the Mkinitcpio configuration uses the base and udev hooks for building the initramfs. Faster boot times can be achieved by replacing them with systemd
Removing Unnecessary Hooks
Use autodetect hook for initramfs which auto detects the require hooks
Using lz4 compression
lz4 compression is slightly faster than zstd or gzip compressions. You can change this in /etc/mkinitcpio.conf
Switch to Dracut
Dracut can generate unified kernel images with smaller size if configured correctly. This allows faster kernel loading.
Using Alternative Init System (Not recommended for beginners)
Systemd started as an init manager but now has absorbed many services and processes. Other init systems such as runit,dinit,s6,etc. are much lighter and allows much faster boot time than systemd
Disable Splash
Disabling Bios Splash and Plymouth Splash can also speed up the boot because splash adds a delay in boot
Disable Terminal Output
On some fast systems using SSDs, The tty could also be a bottlneck meaning lesser the terminal output faster will be the boot.
Staggered Spin-up on HDD
On HDDs staggered spin can also be a problem but it can be fixed by checking dmesg output,i.e, sudo dmesg | grep SSS.
If there is output of this command, then add libahci.ignore_sss=1 to kernel parameters.
Conclusion
This is barely scratching the surface in terms of optimization. You can always do some more optimization. Linux is already way faster than Windows and lighter in terms of resource usage. Then on top of that you can optimize it more to get single digit boot times!