A half-second delay caused a 20% drop in Google search traffic
Misquoted Confidence: medium
Primary source found, but the way it is quoted changes the subject, metric, population or precision.
- Commonly cited as
- "Google found an extra 0.5 seconds cut traffic by 20%"
- True origin
- Greg Linden's blog (reporting Marissa Mayer's talk at Web 2.0, Nov. 2006) — Marissa Mayer at Web 2.0
- Type
- Stat check: A widely repeated statistic traced back to its origin.
- Year
- 2006
- Data as of
- Talk in November 2006
- Last checked
- What the source says
So, Marissa ran an experiment where Google increased the number of search results to thirty. Traffic and revenue from Google searchers in the experimental group dropped by 20%. ... The page with 10 results took .4 seconds to generate. The page with 30 results took .9 seconds. Half a second delay caused a 20% drop in traffic.
- Method & sample
- An anecdote from a conference talk, as written up by an attendee; the test changed the number of results (10 to 30) as well as load time, so speed was not isolated.
- Drift between quote and source
- Cause: the test also tripled the results per page; the speed effect was inferred, not isolated
- Source: a blog write-up of a 2006 talk, not a published study
- Interest
- n/a (personal blog of a former Amazon engineer).
Safe rephrasing
In a 2006 talk, Google's Marissa Mayer described a test where showing 30 results instead of 10 (and pages loading about half a second slower) cut traffic by 20%; speed was not isolated in that test.
Sources we opened
- Greg Linden — Marissa Mayer at Web 2.0 (primary)
Machine-readable: /api/claims/google-half-second-delay-20-percent-traffic-drop.json · Last checked 2026-10-16