This talk was recorded at Scala Days New York, 2016. Follow along on Twitter @scaladays and on the website for more information http://scaladays.org/. Abstract: Common arguments for using more elaborate type systems include safety and documentation. But we will show how more expressive type systems can be used to drive novel powerful optimizations and make the program faster. Based on this principle, we built the Dotty Linker, a whole-program optimizer that represents a breakthrough in optimization of Scala code. We will demonstrate how the linker is capable of reducing the performance overhead of commonly-used Scala features such as generic methods and classes, lazy vals, implicit conversions and closures.