Google apparently runs R on desktops (http://dataspora.com/blog/predictive-analytics-using-r/) and ports it to Python or C++ once their ideas are tested (for production code). Having said that if your list of functions are growing, try packaging up in a library - there are many tutorials available on the web. If your data is becoming big, try using RHIPE (Hadoop integration), bigmemory, snow, or a number of other packages:
http://cran.r-project.org/web/views/HighPerformanceComputing...