The "Follows the sun" background made the plan crawl in Firefox: 23 MB of
textures per frame, sixteen of about twenty picture-cache tiles thrown
away every frame, nine frames per second. The card's own JavaScript was
idle for 89 % of that.
The cost is the outer outline. It is a triple drop-shadow over the
grouped paper footprint, and although the group holds paper silhouettes
only and never changes on hover or pan, the filter lived in the plan's
own layer — so every repaint of the plan re-ran three blur passes over
the whole sheet. One hint moves the filtered paper into its own layer
and unhooks it from the plan's repaints.
Measured on a demo-stand pan (Chromium, CDP, summed RasterTask): 1456.6
ms against a static background's 96.7 ms before, 84.7 ms against 103.2
ms after. The new smoke measures that ratio and fails above two.
The picture does not change: the outline outside the plan matches byte
for byte and the frame's mean colour moves from 176.59 to 176.66 of 255.
Splitting the layer does move the remaining content onto a different
sub-pixel grid, so the diagonal wall hatch anti-aliases differently and
the four day-cycle baselines are re-taken on the beta candidate.
Issue: #532
User-Visible: yes
