[R] Speed up an R code

[Debs Majumdar]

Hello,

  Are there some basic things one can do to speed up a R code? I am new to R and currently going through the following situation.

  I have run a R code on two different machines. I have R 2.12 installed on both.

  Desktop 1 is slightly older and has a dual core processor with 4gigs of RAM. Desktop 2 is newer one and has a xeon processor W3505 with 12gigs of RAM. Both run on Windows 7.

  I don't really see any significant speed up in the newer computer (Desktop 2). In the older one the program took around 5hrs 15 mins and in the newer one it took almost 4hrs 30mins.

 In the newer dekstop, R gives me the following:

> memory.limit()
[1] 1024
> memory.size()
[1] 20.03

 Is something hampering me here? Do I need to increase the limit and size? Can this change be made permanent? Or am I looking at the wrong place? 

 I have never seen my R programs using much CPU or RAM when it runs? If this is not something inherent to R, then I guess I need to write more effiecient codes.

 Suggestions/solutions are welcome.

  Thanks,

  -Debs