so i started a batch top capture and then minimized all my windows (including top capture shell ), system hangs for more than 5 seconds before i can click anything, then i open restore top capture shell top -b > top.log grep PID -A 10 top.log here's some interesting output when all windows minimized , note only middle entries are the relevant parts to the bug PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 9880 rhuddusa 10 -10 1021m 41m 28m S 6 0.5 3:45.07 vlc 3925 rhuddusa 21 1 854m 204m 47m S 4 2.6 6:00.96 chrome 4942 rhuddusa 20 0 922m 86m 22m S 2 1.1 4:33.05 chrome 11039 rhuddusa 20 0 17336 1316 916 R 2 0.0 0:00.01 top 21595 root 20 0 335m 233m 28m S 2 2.9 77:41.10 Xorg 22500 rhuddusa 20 0 1280m 266m 49m S 2 3.3 45:12.97 compiz 22527 rhuddusa 0 -20 410m 6992 4828 S 2 0.1 6:33.12 pulseaudio 1 root 20 0 24456 2444 1380 S 0 0.0 0:01.85 init 2 root 20 0 0 0 0 S 0 0.0 0:00.04 kthreadd 3 root 20 0 0 0 0 S 0 0.0 0:03.93 ksoftirqd/0 -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21595 root 20 0 340m 238m 33m R 23 3.0 77:41.79 Xorg 22500 rhuddusa 20 0 1280m 266m 49m R 16 3.3 45:13.45 compiz 9880 rhuddusa 10 -10 1021m 41m 28m S 5 0.5 3:45.23 vlc 10935 rhuddusa 20 0 522m 16m 10m S 4 0.2 0:00.88 gnome-terminal 11015 rhuddusa 20 0 937m 119m 24m S 3 1.5 0:02.41 chrome 22527 rhuddusa 0 -20 410m 6992 4828 S 3 0.1 6:33.21 pulseaudio 3925 rhuddusa 21 1 859m 203m 47m S 1 2.6 6:01.00 chrome 22535 rhuddusa 20 0 431m 11m 7320 S 1 0.1 2:26.00 bamfdaemon 22542 rhuddusa 20 0 293m 12m 8016 S 1 0.2 1:52.52 gtk-window-deco 22481 rhuddusa 20 0 1072m 370m 11m S 1 4.6 5:37.78 gnome-settings- -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21595 root 20 0 340m 238m 33m R 83 3.0 77:44.30 Xorg 22535 rhuddusa 20 0 431m 11m 7320 S 38 0.1 2:27.16 bamfdaemon 10935 rhuddusa 20 0 522m 16m 10m S 23 0.2 0:01.56 gnome-terminal 22500 rhuddusa 20 0 1280m 266m 49m S 23 3.3 45:14.13 compiz 22471 rhuddusa 20 0 26184 2472 624 R 17 0.0 0:21.52 dbus-daemon 22542 rhuddusa 20 0 293m 12m 8016 S 12 0.2 1:52.87 gtk-window-deco 22481 rhuddusa 20 0 1072m 370m 11m S 7 4.6 5:37.98 gnome-settings- 22553 rhuddusa 20 0 461m 16m 10m S 6 0.2 0:23.29 unity-panel-ser 9880 rhuddusa 10 -10 1021m 41m 28m S 6 0.5 3:45.40 vlc 22555 rhuddusa 20 0 680m 4448 3424 R 4 0.1 0:02.47 hud-service -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21595 root 20 0 335m 233m 28m R 90 2.9 77:47.00 Xorg 22535 rhuddusa 20 0 431m 11m 7320 S 51 0.1 2:28.69 bamfdaemon 22471 rhuddusa 20 0 26184 2472 624 R 23 0.0 0:22.21 dbus-daemon 22542 rhuddusa 20 0 293m 12m 8016 R 19 0.2 1:53.45 gtk-window-deco 22500 rhuddusa 20 0 1280m 266m 49m S 19 3.3 45:14.70 compiz 10935 rhuddusa 20 0 522m 16m 10m S 17 0.2 0:02.07 gnome-terminal 22553 rhuddusa 20 0 461m 16m 10m S 12 0.2 0:23.66 unity-panel-ser 22481 rhuddusa 20 0 1072m 370m 11m S 7 4.6 5:38.19 gnome-settings- 9880 rhuddusa 10 -10 1021m 41m 28m S 6 0.5 3:45.58 vlc 22555 rhuddusa 20 0 680m 4448 3424 S 6 0.1 0:02.65 hud-service -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21595 root 20 0 500m 398m 28m R 92 5.0 77:49.76 Xorg 22535 rhuddusa 20 0 431m 11m 7320 S 46 0.1 2:30.07 bamfdaemon 22471 rhuddusa 20 0 26288 2616 624 R 21 0.0 0:22.84 dbus-daemon 22500 rhuddusa 20 0 1280m 266m 49m R 19 3.3 45:15.27 compiz 22542 rhuddusa 20 0 293m 12m 8016 R 18 0.2 1:53.99 gtk-window-deco 10935 rhuddusa 20 0 522m 16m 10m R 17 0.2 0:02.58 gnome-terminal 22553 rhuddusa 20 0 461m 16m 10m S 14 0.2 0:24.08 unity-panel-ser 22481 rhuddusa 20 0 1072m 370m 11m S 6 4.6 5:38.38 gnome-settings- 22555 rhuddusa 20 0 680m 4448 3424 S 6 0.1 0:02.83 hud-service 9880 rhuddusa 10 -10 1021m 41m 28m S 5 0.5 3:45.74 vlc -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21595 root 20 0 505m 403m 28m R 86 5.1 77:52.35 Xorg 22535 rhuddusa 20 0 431m 11m 7320 S 47 0.1 2:31.48 bamfdaemon 22500 rhuddusa 20 0 1280m 266m 49m S 25 3.3 45:16.02 compiz 10935 rhuddusa 20 0 522m 16m 10m S 24 0.2 0:03.30 gnome-terminal 22471 rhuddusa 20 0 26288 2616 624 S 23 0.0 0:23.52 dbus-daemon 22553 rhuddusa 20 0 461m 16m 10m S 16 0.2 0:24.57 unity-panel-ser 22542 rhuddusa 20 0 293m 12m 8016 S 12 0.2 1:54.35 gtk-window-deco 22481 rhuddusa 20 0 1072m 370m 11m S 7 4.6 5:38.58 gnome-settings- 9880 rhuddusa 10 -10 1021m 41m 28m S 6 0.5 3:45.91 vlc 22555 rhuddusa 20 0 680m 4448 3424 S 3 0.1 0:02.93 hud-service -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21595 root 20 0 505m 403m 28m R 99 5.1 77:55.32 Xorg 22535 rhuddusa 20 0 431m 11m 7320 S 11 0.1 2:31.80 bamfdaemon 22500 rhuddusa 20 0 1280m 267m 49m S 10 3.4 45:16.33 compiz 22471 rhuddusa 20 0 26236 2628 624 S 6 0.0 0:23.70 dbus-daemon 9880 rhuddusa 10 -10 1021m 41m 28m S 3 0.5 3:46.00 vlc 22553 rhuddusa 20 0 461m 16m 10m S 2 0.2 0:24.64 unity-panel-ser 22542 rhuddusa 20 0 293m 12m 8016 S 2 0.2 1:54.41 gtk-window-deco 10935 rhuddusa 20 0 522m 16m 10m S 2 0.2 0:03.35 gnome-terminal 11015 rhuddusa 20 0 930m 94m 19m S 1 1.2 0:02.63 chrome 22527 rhuddusa 0 -20 410m 6992 4828 S 1 0.1 6:33.57 pulseaudio -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 22535 rhuddusa 20 0 431m 11m 7320 S 59 0.1 2:33.59 bamfdaemon 22500 rhuddusa 20 0 1280m 268m 49m S 46 3.4 45:17.71 compiz 22471 rhuddusa 20 0 26236 2628 624 S 33 0.0 0:24.68 dbus-daemon 21595 root 20 0 505m 403m 28m S 19 5.1 77:55.89 Xorg 22553 rhuddusa 20 0 461m 16m 10m S 9 0.2 0:24.91 unity-panel-ser 9880 rhuddusa 10 -10 1021m 41m 28m S 5 0.5 3:46.14 vlc 22527 rhuddusa 0 -20 410m 6992 4828 S 3 0.1 6:33.67 pulseaudio 11015 rhuddusa 20 0 930m 94m 19m S 2 1.2 0:02.69 chrome 11039 rhuddusa 20 0 17344 1340 932 R 1 0.0 0:00.08 top 3925 rhuddusa 21 1 854m 204m 47m S 0 2.6 6:01.36 chrome -- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 22535 rhuddusa 20 0 431m 11m 7320 S 46 0.1 2:34.97 bamfdaemon 22471 rhuddusa 20 0 26236 2628 624 S 28 0.0 0:25.51 dbus-daemon 22500 rhuddusa 20 0 1280m 268m 49m S 27 3.4 45:18.52 compiz 21595 root 20 0 505m 403m 28m R 21 5.1 77:56.53 Xorg 9880 rhuddusa 10 -10 1021m 41m 28m S 4 0.5 3:46.27 vlc 22527 rhuddusa 0 -20 410m 6992 4828 S 3 0.1 6:33.75 pulseaudio 11015 rhuddusa 20 0 930m 94m 19m S 1 1.2 0:02.72 chrome 4183 rhuddusa 21 1 1214m 43m 10m S 0 0.5 17:33.92 chrome 9977 root 20 0 0 0 0 S 0 0.0 0:00.37 kworker/6:1 10935 rhuddusa 20 0 522m 16m 10m S 0 0.2 0:03.36 gnome-terminal