title: Preventing performance regressions in R
body: <p>What is a good workflow for detecting performance regressions in R packages?  Ideally, I'm looking for something that integrates with <code>R CMD check</code> that alerts me when I have introduced a significant performance regression in my code.</p>
  
  <p>What is a good workflow in general? What other languages provide good tools?  Is it something that can be built on top unit testing, or that is usually done separately?</p>