UX experiments / Craft & speed
Craft & speed · Randomized slowdown experiment
Does 100 milliseconds of page speed change revenue?
Pages loaded 100 milliseconds slower for a random group. Did revenue move?
Make your call. Which version won, and why? Decide before you open the result. Guessing first is what trains your judgment.
Made your call? See the result
Every 100ms of speed was worth 0.6% of revenue.
What happened
Bing deliberately slowed pages for randomized groups by 100ms and 250ms for two weeks. The relationship was consistent enough to put a dollar value on speed.
Why it worked
People don't consciously notice 0.1s, but they search, read and click less when everything feels a bit heavier.
The takeaway
Perceived speed is part of the design. Spec it like spacing.
Source
- Adrian Colyer · Seven rules of thumb for web site experimenters (blog.acolyer.org)
More experiments to call
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