App Startup Time
PERFORMANCE › Runtime
Cold/warm/hot starts, pre-first-frame work, and how to measure and speed up launch.
Startup time is a top Android Vitals metric and a frequent interview topic because slow launches directly hurt retention and Play visibility. Interviewers probe whether you understand the three launch states, exactly what runs before the first frame, and the concrete tools (Macrobenchmark, baseline profiles, the splash screen API, App Startup library) used to diagnose and fix it. Strong answers tie a symptom to a precise mechanism and metric rather than vague 'optimize onCreate' advice.
What this covers
- Distinguish cold vs warm vs hot start and what work each repeats
- What runs before the first frame: process fork, Application.onCreate, content providers, App Startup
- TTID vs TTFD and signalling full draw with reportFullyDrawn()
- Measuring startup with Macrobenchmark, the Displayed logcat line, and Perfetto
- The splash screen API replacing custom splash activities on Android 12+
- Baseline profiles and lazy initialization to cut the critical startup path
Study this topic
- App Startup Time explained: the guided lesson
- 14 practice quiz questions
- 9 revision flashcards
- App Startup Time interview questions and answers