慢的启动和登录时间Ubuntu 16.04

Ubuntu 16.04 64位从“登录”屏幕到桌面大约需要20秒，从grub到登录屏幕大约需要20秒，

告诉我可以安全禁用的服务，我不经常使用virtualbox和bluetooth，其他所有东西都被使用，例如打印机，wifi等
。systemd-analyze

Startup finished in 5.145s (kernel) + 14.138s (userspace) = 19.284s

和输出

systemd-analyze blame


 5.837s accounts-daemon.service
          5.444s dev-sda6.device
          4.864s grub-common.service
          4.105s lightdm.service
          4.075s ModemManager.service
          4.001s preload.service
          3.844s apparmor.service
          3.566s networking.service
          3.468s apport.service
          3.332s ondemand.service
          3.272s rsyslog.service
          3.269s systemd-logind.service
          3.253s alsa-restore.service
          3.241s gpu-manager.service
          3.226s avahi-daemon.service
          3.185s systemd-user-sessions.service
          3.185s pppd-dns.service
          2.508s NetworkManager.service
          2.003s user@1000.service
          1.640s plymouth-quit-wait.service
          1.245s colord.service
           712ms systemd-update-utmp.service
           687ms systemd-udevd.service
           669ms udisks2.service
           632ms polkitd.service
           602ms brltty.service
           572ms systemd-localed.service
           567ms systemd-backlight@backlight:intel_backlight.service
           543ms systemd-rfkill.service
           527ms systemd-tmpfiles-setup-dev.service
           519ms thermald.service
           490ms systemd-tmpfiles-setup.service
           464ms systemd-modules-load.service
           454ms systemd-tmpfiles-clean.service
           450ms systemd-timesyncd.service
           428ms systemd-journald.service
           371ms wpa_supplicant.service
           340ms ufw.service
           317ms systemd-random-seed.service
           284ms console-setup.service
           281ms plymouth-start.service
           270ms dev-hugepages.mount
           270ms sys-kernel-debug.mount
           224ms systemd-udev-trigger.service
           177ms dev-mqueue.mount
           168ms plymouth-read-write.service
           165ms upower.service
           131ms dns-clean.service
           103ms systemd-sysctl.service
           102ms dev-disk-by\x2duuid-8bd6db03\x2da87b\x2d4614\x2d927a\x2dd5916f3
            68ms systemd-hostnamed.service
            49ms systemd-journal-flush.service
            47ms kmod-static-nodes.service
            47ms snapd.socket
            32ms systemd-remount-fs.service
            28ms rc-local.service
            10ms resolvconf.service
            10ms rtkit-daemon.service
             9ms systemd-update-utmp-runlevel.service
             6ms ureadahead-stop.service
             4ms sys-fs-fuse-connections.mount lines 39-61/61 (END)

以及：

systemd-analyze critical-chain

the time after the unit is active or started is printed after the "@" character.
The time the unit takes to start is printed after the "+" character.

graphical.target @14.124s
└─lightdm.service @10.018s +4.105s
  └─systemd-user-sessions.service @6.731s +3.185s
    └─basic.target @6.625s
      └─sockets.target @6.625s
        └─snapd.socket @6.576s +47ms
          └─sysinit.target @6.574s
            └─swap.target @6.574s
              └─dev-disk-by\x2duuid-8bd6db03\x2da87b\x2d4614\x2d927a\x2dd5916f3c
                └─dev-disk-by\x2duuid-8bd6db03\x2da87b\x2d4614\x2d927a\x2dd5916f
lines 1-13/13 (END)

我正在使用7200 RPM的硬盘，我认为启动时间还可以，但是登录屏幕后，我必须经过20秒的黑屏，我已经禁用了一些启动项，例如ORCA，BLUETOOTH，备份监视器，可访问性等，个人文件共享和用户文件夹更新等，仍然没有任何改善，如何诊断和处理问题的元凶。

尝试删除一些未使用的依赖项和孤立包。这会有所帮助。
就我而言，它奏效了。跑：

sudo apt autoremove && sudo apt autoclean

另外，您可以安装Gtkorphan（sudo apt-get install gtkorphan）删除其他应用程序留下的所有孤立软件包和依赖项。