Unconditionally updating element attrs causes side effects

[spiffytech]

Sandbox

Every time an <img>'s src attribute is set (even if unchanged), that image gets loaded again (load event is fired). If the image wasn't successfully loaded last time, the browser hits the network to try loading it again.

Because Forgo sets all attributes during every render, every render triggers the onload handler, and additionally hits the network if the image 404'd or similar.

In the sandbox you can see in the console after pressing buttons (2) or (3) that the image events fire based on attrs changes, regardless of whether Forgo is involved. Button (1) shows the 404 behavior in the network inspector.