Merge "Preload only visible thumbnails and task icons. (Bug 17672056, Bug 18291345)" into lmp-mr1-dev automerge: 147de3a
automerge: 6a601c9

* commit '6a601c9ee8cee46680417dc450e9bb64c86a1b09':
  Preload only visible thumbnails and task icons. (Bug 17672056, Bug 18291345)