With UI refresh enabled

What steps will reproduce the problem?
(1) Open the tab grid
(2) Open a new tab
(3) Repeat 3-4 times

What is the expected result?
The new tab opening animation should present a screen shot of the new tab.

What happens instead?
A white page is presented during the open animation. This doesn't always happen for the first 1-2 tabs opened. It is consistently reproducible for the following ones.