The canvas shows first, images follow. Opening a canvas no longer waits for every thumbnail to finish downloading — the canvas appears right away and images fill in in the background. The more nodes you have and the slower your connection, the bigger the difference.
Canvas media is cached long-term. Images on your canvas are now kept in your browser's cache, so reopening the same canvas barely re-downloads anything.
On a flaky connection you won't be left staring at a loading bar anymore.

Canvases open faster — the canvas appears first, images follow