R package that automatically uses several cores?

Question

I have noticed that R only uses one core while executing one of my programs which requires lots of calculations. I would like to take advantage of my multi-core processor to

Answer 1

R can only make use of multiple cores with the help of add-on packages, and only for some types of operation. The options are discussed in detail on the High Performance Computing Task View on CRAN

Update: From R Version 2.14.0 add-on packages are not necessarily required due to the inclusion of the parallel package as a recommended package shipped with R. parallel includes functionality from the multicore and snow packages, largely unchanged.