Implicit wrappers have long been an issue for this sort of optimisation, although I was pleased to read that the new JVM escape analysis feature seems to deal w

Implicit wrappers have long been an issue for this sort of optimisation, although I was pleased to read that the new JVM escape analysis feature seems to deal with that very effectively: http://www.decodified.com/scala/2010/08/27/scala-rich-wrapping-performance.html http://www.decodified.com/scala/2010/08/27/scala-rich-wrappi... As other comments have noted you can generally degrade to writing near-Java code and the results will be basically the same bytecode. I'm sure there are exceptions but if you want to, you can avoid object creation. Implicit conversions are one of those cases which will not be called out as a warning or similar, though, so something to be careful of.