Research brief: Website Performance & Revenue — defensible evidence for KW small-business owners (piece 17)

Status: Research material — not a finished article. Compiled May 22, 2026.

TL;DR

• Faster pages move money, but the size of the effect is sector- and severity-dependent. See Deloitte/Google "Milliseconds Make Millions" (2020): 0.1s improvement → 8.4% retail conversion lift, 10.1% travel, Vodafone A/B test (2021): 31% LCP improvement → 8% more sales, 15% better lead-rate, 11% better cart-rate, Rakuten 24 (2022 A/B test): CWV optimization → +33.13% conversion rate, +53.37% revenue per visitor, -35.12% exit rate, redBus (2023): INP improved ~72% on search page → +7% sales (6-7.2% CR uplift across operating countries).
• Core Web Vitals are a real but small Google ranking factor and a much bigger user-behaviour factor — see Core Web Vitals is a tiebreaker-class Google ranking factor, not a heavy lever — independent studies (Perficient, AWR, Backlinko) corroborate.
• For a $5K WordPress refresh vs $20K custom build, performance alone does not justify the custom build. See $5K WordPress refresh vs $20K custom build — performance alone does not justify the $15K delta.

Critically, this brief also catalogues what the evidence does NOT support — see Speed/conversion stats commonly cited but NOT supported by primary evidence in 2026 — Candid will not quote these — so client conversations stop on solid ground.