Viewport units (vh/vw) were a mistake to add to CSS; slower than alternatives (layout systems) assuming good implementation
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@davidbaron Interesting. What makes them slow? What is a "layout system" in this context? Might need > 140 chars.
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Replying to @SimonSapin
@SimonSapin Viewport units need recomputation of style data for size changes plus the work the layout system (block, flex, &c) requires.

Oct 22, 2014 · 2:19 AM UTC

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Replying to @davidbaron
@davidbaron @SimonSapin size changes in practice are mainly device orientation switches. Devs frantically resizing the window doesn't count
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@alanstearns @SimonSapin Also things like mobile keyboards, URL bars, status bars appearing and disappearing (with animation)
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Replying to @davidbaron
@davidbaron Is the extra recomp (when they're actually used) that significant in your view? Seems negligible compared to layout @SimonSapin