[ESS] loading ESS mode conditional on certain file names

[Adrian Dragulescu]

Hello,

When I open a file in Emacs, it takes me about 10 seconds, and I would 
like to speed up the process as much as possible.  I've indentified two 
possible issues related to ESS.

1) I have (require 'ess-site) in my .emacs file.  Can I make it 
conditional on the file extension?  I would like to run this require 
command only if file I open has a .R or .r extension.  If I double-click 
on a txt file, I don't need ESS.  I just want to open the file fast. 
Without the ess require statement my start up is 2 seconds.

2) It seems that ESS is searching for R on my system.  From my *Messages* 
buffer:
Finding all versions of R on your system...
Sorry, no version of R could be found on your system.
I have a non-standard network installation of R.  How should I point ESS 
to the right location, to save the searching time.

I am using Emacs 22.3 & ESS 5.3.11 on Win XP.

Thank you,
Adrian