A highly efficient bug fixing process and quick release cycles are considered key properties of the open source software development methodology. In this paper, we study the relation between code activities (such as lines of code added per commit), bug fixing activities, and software release dates in a subset of open source projects. To study the phenomenon, we gathered a large data set about the evolution of 5 major open source projects. We compared activities by means of a burst detection technique to discover temporal peaks in time-series. We found quick adaptation of issue tracking activities in proximity of releases, and a distribution of coding activities across releases. Results show the importance of the application type/domain for the evaluation of the development process.