Effect snapshot
| Intervention | Increase page load time by ~1 second |
| Outcome | Bounce rate |
| Effect | 7–11 percent relative increase |
| Confidence | estimate |
| Context | Aggregated web performance studies, mobile landing pages |
Sources
What changes
Slower first paint and interactive delay cause more users to leave before seeing the value proposition.
Where it hits hardest
- Paid ad landing pages (high impatience, single intent)
- Mobile networks with variable latency
- Pages with heavy hero images and third-party scripts
Practical takeaway
Speed work is often higher leverage than button-color tests. Treat 7–11% bounce increase per +1s as a directional planning figure.