[R] Ubuntu vs. Windows

[Doran, Harold]

Dear List:

I am very much a unix neophyte, but recently had a Ubuntu box installed
in my office. I commonly use Windows XP with 3 GB RAM on my machine and
the Ubuntu machine is exactly the same as my windows box (e.g.,
processor and RAM) as far as I can tell.

Now, I recently had to run a very large lmer analysis using my windows
machine, but was unable to due to memory limitations, even after
increasing all the memory limits in R (which I think is a 2gig max
according to the FAQ for windows). So, to make this computationally
feasible, I had to sample from my very big data set and then run the
analysis. Even still, it would take something on the order of 45 mins to
1 hr to get parameter estimates. (BTW, SAS Proc nlmixed was even worse
and kept giving execution errors until the data set was very small and
then it ran for a long time)

However, I just ran the same analysis on the Ubuntu machine with the
full, complete data set, which is very big and lmer gave me back
parameter estimates in less than 5 minutes. 

Because I have so little experience with Ubuntu, I am quite pleased and
would like to understand this a bit better. Does this occur because R is
a bit friendlier with unix somehow? Or, is this occuring because unix
somehow has more efficient methods for memory allocation?

I wish I knew enough to even ask the right questions. So, I welcome any
enlightenment members may add.