Superhuman Is Built for Speed

Summary

Gmail creator Paul Buchheit established the 100ms rule: interactions faster than 100ms feel instantaneous. Superhuman targets sub-50ms when possible, despite running atop Gmail and Outlook APIs. The business case is clear—Amazon found every 100ms delay costs 1% in sales.

Key Points

• The 100ms threshold separates "fast" from "instant" in user perception. Below this mark, interfaces feel like direct manipulation rather than request-response cycles.
• Local caching defeats latency by storing email databases offline. No round-trip to servers means no propagation delay, transmission bottlenecks, or network hops.
• Preloading anticipates behavior by fetching likely-next email threads before users request them. The data arrives before intention becomes action.
• Keyboard shortcuts outpace mouse navigation because they eliminate the visual search, cursor movement, and click confirmation that pointing devices require.
• Command palettes (Cmd+K) compress multi-step workflows into search queries, trading menu hierarchy traversal for direct intent expression.

Related

The local-first approach to speed connects directly to local-first-software, where instant responsiveness ranks first among the seven ideals for software that respects user ownership.