UK Address Autocomplete Latency & Performance Benchmarks
Address autocomplete is the highest-frequency interaction in modern checkout and onboarding flows. Every 100ms of keystroke lag increases form abandonment. We benchmarked FastAddress UK against leading UK postcode providers across 21.1+ million address records.
Median Response Latency (P50)
Lower is better. Measures round-trip server processing time.
Test FastAddress UK from Your Own Browser
Execute real-time queries against the live API directly from your current network connection.
Feature & Architectural Comparison Matrix
| Feature / Capability | FastAddress UK | GetAddress.io | Ideal Postcodes | Loqate |
|---|---|---|---|---|
| Underlying Engine | Go + SQLite FTS5 | PostgreSQL / Ruby | Elasticsearch / Node | Legacy Enterprise Stack |
| Database Size | 21.1M+ Verified Records | ~30M PAF | ~30M PAF | Global PAF |
| OS UPRN Mapping | ✅ Included Free | ❌ Paid Extra | ✅ Included | ⚠️ Higher Tier Only |
| WGS84 Coordinates | ✅ Included Free | ✅ Included | ✅ Included | ✅ Included |
| Missing Street Interpolation | ✅ Dynamic Fallback Engine | ❌ Exact Only | ⚠️ Fuzzy Fallback | ⚠️ Fuzzy Fallback |
| In-Memory LRU Cache | ✅ O(1) Prefix Cache | ⚠️ Redis Tier | ⚠️ HTTP Cache | ⚠️ CDN Edge |
How We Achieved Sub-15ms Address Lookups
Engineered from bare metal for zero-allocation concurrency and deterministic response times.
1. Pure Go & Zero-CGO SQLite
Traditional APIs introduce thread pool context-switching overhead. FastAddress uses pure Go bindings to query a high-density SQLite FTS5 database, executing in-process without CGO bridging delays.
2. In-Memory LRU Prefix Cache
High-frequency prefix queries (e.g. "SW1A", "10 Down", "M1 1") are served from a thread-safe in-memory LRU cache in < 0.2ms, avoiding disk I/O entirely for repeated keystrokes.
3. Integrated OS UPRN & WGS84 Coords
Instead of requiring secondary API hops to fetch coordinates and UPRNs, every FastAddress record contains pre-computed Ordnance Survey IDs and float coordinates in a single payload.
4. Smart Fallback Interpolation
When a building number is unlisted, our geometric interpolation engine dynamically projects the coordinate along the street axis at postcode resolution, eliminating zero-result failures.
Frequently Asked Benchmark Questions
Technical details on testing methodology and test reproduction.
How were these benchmarks measured?
Benchmarks measure round-trip HTTP request time over standard HTTPS connections from UK and European edge locations. Concurrency runs simulate 10 to 50 concurrent keystrokes against a production database of 21.1 million UK address records.
Why do legacy address APIs have 100ms+ latency?
Most legacy address services wrap older relational database systems (PostgreSQL, SQL Server) behind multi-tier enterprise APIs with XML serialization, authentication gateways, and rate-limiting sidecars.
Can I reproduce these benchmarks?
Yes. You can run the interactive browser test above, execute curl queries with HTTP timing flags, or clone our open-source benchmark suite from GitHub.
How does this affect checkout conversion rates?
Studies show that reducing address lookup latency from 200ms to under 25ms eliminates visual typing stutter, increasing mobile checkout completion rates by up to 21%.