提出的 dublicate 并没有回答我的问题，因为尽管 apt-daily.service 和 apt-daily-upgrade.service 很可能是罪魁祸首，但 systemd-analyze blame 的输出并不能解释为什么内核需要几分钟。
内核部分是否还包括系统等待我输入加密密码的时间？
bruni@PROX15:~$ systemd-analyze
Startup finished in 5.832s (firmware) + 5.182s (loader) + 9min 6.295s (kernel) + 1min 18.571s (userspace) = 10min 35.882s
graphical.target reached after 9.110s in userspace
systemd-analyze 指责没有任何个人会在几分钟内发生。
这是相当高规格的硬件。
bruni@PROX15:uname -a
Linux PROX15 5.3.0-51-generic #44~18.04.2-Ubuntu SMP Thu Apr 23 14:27:18 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
bruni@PROX15:~$ systemd-analyze blame
45.155s apt-daily.service
24.310s apt-daily-upgrade.service
6.287s NetworkManager-wait-online.service
1.668s dev-mapper-kubuntu\x2d\x2dvg\x2droot.device
1.173s systemd-journal-flush.service
1.045s snapd.service
761ms dev-loop1.device
721ms dev-loop4.device
708ms dev-loop5.device
680ms mariadb.service
676ms dev-loop6.device
669ms dev-loop2.device
653ms dev-loop0.device
643ms dev-loop3.device
585ms dev-loop8.device
570ms dev-loop7.device
556ms vboxdrv.service
540ms dev-loop9.device
526ms mpd.service
516ms networkd-dispatcher.service
504ms snap-core18-1754.mount
490ms snap-pdftk-9.mount
471ms dev-loop11.device
468ms snap-scrcpy-217.mount
461ms systemd-logind.service
459ms dev-loop10.device
427ms gpu-manager.service
411ms ModemManager.service
334ms snap-snapd-7264.mount
311ms NetworkManager.service
310ms snap-scrcpy-211.mount
310ms ufw.service
308ms snap-core18-1705.mount
305ms udisks2.service
266ms snap-core-8935.mount
257ms snap-gnome\x2d3\x2d28\x2d1804-116.mount
256ms snap-gtk\x2dcommon\x2dthemes-1506.mount
240ms snap-snapd-6953.mount
234ms upower.service
222ms snap-rambox-13.mount
212ms snap-core-9066.mount
206ms accounts-daemon.service
165ms thermald.service
160ms wpa_supplicant.service
151ms systemd-tmpfiles-setup-dev.service
134ms grub-common.service
126ms keyboard-setup.service
120ms nvidia-persistenced.service
116ms systemd-modules-load.service
115ms tlp.service
109ms systemd-udevd.service
105ms apparmor.service
....
PS1：请注意，我并不是一个狂热的启动时间优化者，但这对我来说似乎不太正确......
PS2：如果我在初始启动后重新启动：
bruni@PROX15:~$ systemd-analyze
Startup finished in 8.433s (firmware) + 4.958s (loader) + 12.884s (kernel) + 14.714s (userspace) = 40.991s
graphical.target reached after 14.627s in userspace
PS3：
Startup finished in 5.900s (firmware) + 5.046s (loader) + 18min 18.402s (kernel) + 40.122s (userspace) = 19min 9.472s
用户空间中，graphic.target 在 10.695 秒后达到
根据评论要求，输出 systemd-analyze critical-chain。
graphical.target @10.695s
└─multi-user.target @10.694s
└─kerneloops.service @10.681s +13ms
└─network-online.target @10.679s
└─NetworkManager-wait-online.service @4.394s +6.284s
└─NetworkManager.service @4.142s +246ms
└─dbus.service @3.880s
└─basic.target @3.868s
└─sockets.target @3.868s
└─snapd.socket @3.862s +4ms
└─sysinit.target @3.859s
└─apparmor.service @3.673s +185ms
└─local-fs.target @3.670s
└─run-user-1001-doc.mount @30.922s
└─run-user-1001.mount @29.096s
└─swap.target @3.100s
└─dev-mapper-kubuntu\x2d\x2dvg\x2dswap_1.swap @3.045s +54ms
└─dev-mapper-kubuntu\x2d\x2dvg\x2dswap_1.device @3.033s