Mobile App Launch Performance II
Article Summary
At Farfetch, a 0.1 second delay in warm app launch costs $4.2M annually. That's less time than it takes to blink.
The Farfetch mobile team breaks down the business case for app launch performance, translating milliseconds into dollars. With 1 million+ daily launches across their iOS app, they've quantified exactly how much every second of delay costs in conversion rates and customer relationships.
Key Takeaways
- Every 1 second delay in app launch reduces conversion rate by 7%
- Farfetch saves 12 days of cumulative launch time per 1 second improvement
- Cold launch exceeding 2 seconds creates $350K opportunity cost for new users
- Performance budgets enable trade-off discussions between engineering and product teams
- MetricKit and Instruments provide development-time performance measurement on iOS
Measuring app launch performance and setting budgets transforms performance from an afterthought into quantifiable business decisions that engineering and product teams can negotiate together.
About This Article
Farfetch's iOS app launches over 1 million times daily and gets 100,000 new downloads per release. App launch is the first experience users have, so it matters most.
The team set TTI baselines at 2 seconds for cold launch and 1.5 seconds for warm launch. They created performance budgets by adding up inner stage budgets to get their targets.
Research shows 19% of customers uninstall apps that take over 5 seconds to load. Performance budgets give teams a common language for making trade-off decisions.
