[R] which operating system + computer specifications lead to the best performance for R?

[Marc Jekel]

Dear R Fans,

I have the opportunity to buy a new computer for my simulations in R. My 
goal is to get the execution of R code as fast as possible. I know that 
the number of cores and the working memory capacity are crucial for 
computer performance but maybe someone has experience/knowledge which 
comp specifications are especially crucial (especially in relation to 
R). Is there any knowledge on the performance of R for different 
operating systems (Linux, Win, Mac etc.) resp. is performance dependent 
on the operating system at all? Even small differences in performance 
(i.e., speed of calculations) matter for me (quite large datasets + 
repeated calculations etc.).

Thank you for any hint, it is appreciated!

Best,

Marc