It's easy to appreciate the productivity gains of Kotlin, but what are the downsides in code size and execution time? In this session I look at the (JVM) code generated by the Kotlin compiler and benchmark results to help answer these questions. Duncan has been programming professionally for 25 years. He was lucky enough to ride the Object-Oriented wave of the 90s, the Agile wave of the 00s, and what he is convinced will be called the Distributed-Functional wave of the, erm 10s.