R code to try to compile and speed up

[fikovnik]

From Luke and Tomas:

r-devel/r-dev-day#101
https://bugs.r-project.org/show_bug.cgi?id=17691

Another one from Uwe:

urt's example from earlier today:
Actually, it takes ~ 25 minutes to calculate the recursive reverse
dependences for all CRAN package (on my aged Windows laptop):

a <- available.packages()
system.time(revdps <- tools:::package_dependencies(a[,1], db=a,
which="most", recursive=TRUE))

user system elapsed

#1132.94 329.14 1606.40

Best,
Uwe

[kalibera]

One could indeed also play with the previous version of the code (see svn, before I did some performance optimization/hack).