Chrome OS 10575.12.0, 67.0.3396.16

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1)Open feedback report page with Shift+Alt+I at sign-in screen
(2)Observe the screenshot preview.
(3)

Expected Result:

Actual Result:
Screenshot preview take so long to load.
After login, Screenshot preview loads very quick.

How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
Always
What is the impact to the user, and is there a workaround? If so, what is
it?

Please provide any additional information below. Attach a screen shot or
log if possible.

For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.