Content Meta Preview blinking while loading items in UDW

Prereq.: For best results use symfony_env dev and Firefox on EE demo.

Steps:

1. Go to Content / Content structure.
2. Click Browse to open UDW.
3. Click Home.
4. Click quickly Products and all the items up to Places & Tastes and the end.
5. Observe the Content Meta Preview.

Actual: The CMP area "blinks" displaying preview for all the items selected.
Expected: The other preview request are cancelled.

Recording: http://recordit.co/oNnEa9ZjSV

Remarks: In case of Firefox and dev sometimes Gateway Time-out occurs in UI (screenshot).