[R] Sweave question

[Ralf B]

It seems that Sweave is supposed to be used from Latex and R is called
during the LaTeX compilation process whenever R chunks appear. What
about the other way round? I would like to run it triggered by R. Is
this possible? I understand that this does not correspond to the idea
of literate programming since it means that there is R code running
outside the document, but for my practical approach, I would like to
use Sweave more like a report extension at the end of my already
existing R scripts that combined a number of diagrams to a pdf file.

My second question is, does Sweave create a potential performance
bottleneck when used with very big data analysis compared with when
using R directly?

Ralf