marcheu@ does this look like a graphics issue? If not feel free to reassign.

There isn't enough information, for example which device is it, and can you file feedback report ? Thanks

(by the way, if this was samus, we fixed this bug last week)

I am experiencing the same issue. From cold boot to login screen in about 5-6 seconds. After entering the password successfully, the screen (two monitors in my case) both go blank for about 20 seconds before the desktop appears. I even notice that the monitors enter power saving mode (no video signal at all?) when this happens. Here's my detailed info:

Google Chrome	 59.0.3071.82 (Official Build) beta (64-bit)
Revision	 0
Platform	 9460.57.0 (Official Build) beta-channel guado
Firmware Version Google_Guado.6301.108.4
JavaScript	 V8 5.9.211.30
Flash	         26.0.0.102 /opt/google/chrome/pepper/libpepflashplayer.so
User Agent	 Mozilla/5.0 (X11; CrOS x86_64 9460.57.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.82 Safari/537.36
Command Line	/opt/google/chrome/chrome --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=26.0.0.102 --ui-prioritize-in-gpu-process --use-gl=egl --gpu-sandbox-failures-fatal=yes --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --max-unused-resource-memory-usage-percentage=5 --login-profile=user --aura-legacy-power-button --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/default_large.jpg --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/default_small.jpg --child-wallpaper-large=/usr/share/chromeos-assets/wallpaper/child_large.jpg --child-wallpaper-small=/usr/share/chromeos-assets/wallpaper/child_small.jpg --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --enable-prefixed-encrypted-media --enable-consumer-kiosk --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --login-user=triune@gmail.com --login-profile=e20db29f23274307e2f8dc84edfd739b35de8800 --flag-switches-begin --enable-device-discovery-notifications --enable-devtools-experiments --enable-fast-unload --enable-google-branded-context-menu --enable-gpu-rasterization --enable-grouped-history --enable-md-feedback --enable-password-generation --enable-sync-app-list --enable-tab-audio-muting --enable-video-player-chromecast-support --enable-webrtc-stun-origin --secondary-ui-md --enable-smooth-scrolling --enable-features=ArcBootCompletedBroadcast,EmojiHandwritingVoiceInput,MaterialDesignBookmarks,MaterialDesignExtensions,MaterialDesignHistory,MaterialDesignSettings,MediaRemoting,MediaRemotingEncrypted,OverlayScrollbar,PreferHtmlOverPlugins,ScrollAnchoring,ShowArcFilesApp,WebRtcHWH264Encoding,WebRtcUseEchoCanceller3 --flag-switches-end --vmodule=*chromeos/login/*=1,auto_enrollment_controller=1,*plugin*=2,*zygote*=1,*/ui/ozone/*=1,*/ui/display/manager/chromeos/*=1,power_button_observer=2,webui_login_view=2,lock_state_controller=2,webui_screen_locker=2,screen_locker=2
Executable Path	/opt/google/chrome/chrome

I have experiences the same thing and it has gotten even worse after the last beta update. 

Google Chrome	60.0.3112.41 (Official Build) beta (64-bit)
Revision	0
Platform	9592.29.0 (Official Build) beta-channel chell
Firmware Version	Google_Chell.7820.253.0
ARC	4104783
JavaScript	V8 6.0.286.19
Flash	26.0.0.126 

It goes black for at least 15 seconds.