I was recently profiling some R code for a friend, and this is a useful summary. They don't show the data on their website, but their white paper (http://r.cs.purdue.edu/pub/ecoop12.pdf) shows the times for R vs Python vs C for some of the code on a popular language bencmark: http://benchmarksgame.alioth.debian.org/

Summarizing the summary of their summary of things that probably shouldn't be summarized:

On average across their tests, Python is 1/50th the speed of C, and R is 1/500th.

R frequently uses 100x to 1000x more heap memory than C.

R code size (number of lines ignoring comments) is usually about 1/2 that of C, which is about the same as Python.

As a second set of data, the site for http://julialang.org/ has some timing comparisons for some similar programs. On their tests, Julia comes out about 1-1.5x slower than of C (frequently equal), Python 3x-30x slower (usually in the middle), and R 4x-500x slower (fairly even distribution).