$ time ./single-loop.r
[1] "1(1000)"
...
[1] "750(1000)"
null device
          1

real	15m47,862s
user	15m45,166s
sys	0m0,188s

#-----------------------

$ time ./single-vec.r 
[1] "1(1000)"
...
[1] "750(1000)"
null device 
          1 

real	1m17,911s
user	1m14,356s
sys	0m2,736s