In reply to Justin Tadlock.

Thanks Justin. I was only concerned about this extra check, as core lazy loading should take priority over everything. Existing JavaScript-based plugins are doing it differently anyway, by using a data-src attribute and a 1px image or a placeholder and then replacing everything if they are within visible threshold. This would also clean up (weed out) older plugins.

I'm sure the speed gain is negligible, but every millisecond counts, especially with Google's move towards shaming slow websites.