$ time ls /long/path/to/bigdir | wc -l
  101645

real    0m0.463s
user    0m0.421s
sys     0m0.078s

$ time perl -e 'opendir(D,"/long/path/to/bigdir");
 @f=readdir D; print "$_\n" for (@f)' | wc -l
  101647

real    0m0.156s
user    0m0.124s
sys     0m0.070s