我在一台双启动机器上安装了 Ubuntu 20.04，启动需要很长时间。我第一次安装它时并没有花那么多时间，所以我开始想知道为什么会发生这种情况。
这是什么systemd-analyze 责备返回：
44.535s plymouth-quit-wait.service
21.380s snapd.service
19.608s dev-sda6.device
16.905s systemd-journal-flush.service
15.430s apt-daily.service
15.290s networkd-dispatcher.service
11.667s udisks2.service
11.560s dev-loop27.device
11.101s dev-loop20.device
11.050s NetworkManager-wait-online.service
11.009s dev-loop28.device
10.990s dev-loop26.device
10.860s dev-loop25.device
10.799s dev-loop11.device
10.733s dev-loop22.device
10.556s dev-loop17.device
10.439s dev-loop8.device
10.323s dev-loop19.device
10.192s dev-loop16.device
10.096s dev-loop24.device
9.903s accounts-daemon.service
9.802s dev-loop21.device
9.677s dev-loop29.device
9.600s dev-loop18.device
9.505s dev-loop9.device
9.449s dev-loop4.device
9.009s dev-loop14.device
9.003s dev-loop23.device
8.603s NetworkManager.service
8.552s dev-loop13.device
8.077s dev-loop3.device
8.034s dev-loop15.device
7.032s dev-loop1.device
6.972s dev-loop7.device
6.850s dev-loop10.device
6.779s polkit.service
6.488s dev-loop2.device
6.407s dev-loop0.device
6.221s dev-loop12.device
6.169s apport-autoreport.service
5.991s apache2.service
5.877s avahi-daemon.service
5.875s bluetooth.service
5.838s dev-loop5.device
5.806s ModemManager.service
5.500s switcheroo-control.service
5.492s thermald.service
5.489s wpa_supplicant.service
5.488s systemd-logind.service
4.938s dev-loop6.device
3.819s grub-common.service
3.630s loadcpufreq.service
3.550s systemd-rfkill.service
3.039s apport.service
2.976s [email protected]
2.482s gdm.service
2.292s rsyslog.service
2.141s gpu-manager.service
2.102s e2scrub_reap.service
2.029s snap-code-58.mount
1.966s plymouth-start.service
1.960s snap-code-59.mount
1.862s snap-core-10859.mount
1.861s snap-core-10908.mount
1.810s systemd-fsck@dev-disk-by\x2duuid-D4FE\x2dF70C.service
1.737s secureboot-db.service
1.712s snap-core18-1944.mount
1.678s systemd-resolved.service
1.605s snap-core18-1988.mount
1.603s snapd.apparmor.service
1.508s snap-core20-875.mount
1.471s snap-core20-904.mount
1.460s upower.service
1.448s snap-exercism-5.mount
1.380s systemd-udevd.service
1.342s snap-figma\x2dlinux-92.mount
1.340s snap-figma\x2dlinux-93.mount
1.303s snap-foliate-1137.mount
1.301s snap-foliate-1163.mount
1.235s snap-gnome\x2d3\x2d28\x2d1804-128.mount
1.109s apparmor.service
1.083s snap-gnome\x2d3\x2d28\x2d1804-145.mount
981ms systemd-modules-load.service
800ms snap-gnome\x2d3\x2d34\x2d1804-60.mount
750ms snap-gnome\x2d3\x2d34\x2d1804-66.mount
713ms systemd-tmpfiles-setup.service
707ms snap-gtk\x2dcommon\x2dthemes-1513.mount
676ms lm-sensors.service
603ms systemd-tmpfiles-setup-dev.service
599ms systemd-sysusers.service
586ms virtualbox.service
585ms snap-gtk\x2dcommon\x2dthemes-1514.mount
571ms systemd-random-seed.service
568ms keyboard-setup.service
567ms systemd-journald.service
550ms snap-kde\x2dframeworks\x2d5\x2dqt\x2d5\x2d14\x2dcore18-4.mount
537ms systemd-user-sessions.service
521ms snap-kde\x2dframeworks\x2d5\x2dqt\x2d5\x2d15\x2dcore20-14.mount
483ms systemd-sysctl.service
474ms systemd-timesyncd.service
431ms grub-initrd-fallback.service
416ms snap-kolourpaint-56.mount
415ms snap-kolourpaint-59.mount
413ms snap-pick\x2dcolour\x2dpicker-238.mount
396ms atopacct.service
394ms snapd.seeded.service
390ms vboxweb.service
376ms snap-spotify-45.mount
371ms systemd-udev-trigger.service
343ms snap-snapd-11107.mount
322ms pppd-dns.service
320ms cpufrequtils.service
292ms dev-hugepages.mount
291ms dev-mqueue.mount
289ms sys-kernel-debug.mount
288ms sys-kernel-tracing.mount
285ms systemd-backlight@backlight:intel_backlight.service
283ms kmod-static-nodes.service
281ms [email protected]
278ms swapfile.swap
262ms snap-vlc-1700.mount
260ms snap-spotify-46.mount
259ms snap-vlc-2103.mount
259ms colord.service
254ms systemd-update-utmp.service
228ms [email protected]
172ms systemd-tmpfiles-clean.service
158ms snap-snapd-11402.mount
154ms kerneloops.service
151ms systemd-remount-fs.service
129ms boot-efi.mount
102ms openvpn.service
99ms phpsessionclean.service
95ms ufw.service
90ms plymouth-read-write.service
87ms setvtrgb.service
82ms console-setup.service
82ms [email protected]
26ms hddtemp.service
23ms [email protected]
18ms rtkit-daemon.service
10ms systemd-update-utmp-runlevel.service
10ms alsa-restore.service
6ms sys-fs-fuse-connections.mount
5ms sys-kernel-config.mount
1ms snapd.socket
我也读过这个答案（由于 plymouth-quit-wait.service + ubuntu 18.04 导致启动缓慢的问题 ）并检查 plymouth-quit-wait.service 正在等待什么：
plymouth-quit-wait.service
● ├─system.slice
● └─sysinit.target
● ├─apparmor.service
● ├─dev-hugepages.mount
● ├─dev-mqueue.mount
● ├─keyboard-setup.service
● ├─kmod-static-nodes.service
● ├─plymouth-read-write.service
● ├─plymouth-start.service
● ├─proc-sys-fs-binfmt_misc.automount
● ├─setvtrgb.service
● ├─sys-fs-fuse-connections.mount
● ├─sys-kernel-config.mount
● ├─sys-kernel-debug.mount
● ├─sys-kernel-tracing.mount
● ├─systemd-ask-password-console.path
● ├─systemd-binfmt.service
● ├─systemd-boot-system-token.service
● ├─systemd-hwdb-update.service
● ├─systemd-journal-flush.service
● ├─systemd-journald.service
● ├─systemd-machine-id-commit.service
● ├─systemd-modules-load.service
● ├─systemd-pstore.service
● ├─systemd-random-seed.service
● ├─systemd-sysctl.service
● ├─systemd-sysusers.service
● ├─systemd-timesyncd.service
● ├─systemd-tmpfiles-setup-dev.service
● ├─systemd-tmpfiles-setup.service
● ├─systemd-udev-trigger.service
● ├─systemd-udevd.service
● ├─systemd-update-utmp.service
● ├─cryptsetup.target
● ├─local-fs.target
● │ ├─-.mount
● │ ├─boot-efi.mount
● │ ├─systemd-fsck-root.service
● │ └─systemd-remount-fs.service
● └─swap.target
● └─swapfile.swap
你能告诉我我能做些什么吗？我是 Ubuntu 新手，所以我真的不知道什么东西可以安全卸载。
谢谢