This video was recorded at Scala Days Berlin 2016 follow us on Twitter @ScalaDays or visit our website for more information http://scaladays.org Abstract: You may have seen the @inline and @specialized annotations used in Scala code, and have some idea that they are added for performance reasons. But the exact details of what they do is not widely known, and it's hard to estimate whether they will provide a real performance benefit to your code. This talk will: explain exactly what the annotations do; provide some examples of how to use them; and use benchmarks to explore how they affect performance. There will also be honourable mentions for some of the more esoteric Scala annotations such as @elidable, @strictfp, @switch and @varargs.