Explore the inner workings of Kotlin in this 35-minute conference talk from Devoxx Poland 2019. Delve into powerful language features that may involve significant behind-the-scenes work, including object allocation and reflection. Learn about tools and techniques to discover hidden complexities in Kotlin code. Examine examples of primitive types, bytecode, memory profiling, lazy properties, unsigned numbers, ranges, inline classes, arrays, extension functions, default parameters, and coroutines. Gain insights into when these features matter for performance and how to effectively use Kotlin's capabilities while being aware of their implications.