Comparative Analysis of Development Cycle Speed in Java and Kotlin Based on IDE Telemetry Data | The Research Blog

A large-scale observational study leveraging IntelliJ IDEA telemetry data reveals that development cycles in Kotlin-oriented projects are generally shorter than in comparable Java-oriented projects, with Kotlin cycles being approximately 15–20% shorter for small to large tasks. The study, conducted on data from about 320,000 developers over 20 months, adopts a rigorous statistical framework to control for potential biases, such as user and project differences, time trends, and task sizes. While the transition to Kotlin does not result in an immediate speedup, Kotlin projects show less degradation in cycle times over time compared to Java projects, which tend to experience considerable cycle-time growth. The research acknowledges its observational nature and potential limitations, such as unobserved team characteristics, and suggests future directions like the use of propensity score matching and exploring the effects in Android Studio. Despite JetBrains' involvement as the creator of Kotlin, the study employs multiple control groups and validity checks to ensure the reliability of its findings.