$ perl -le " for( 1 .. 10 ){ printf qq{%d.%d.%d.%d\n}, $_ , $_, $_, $_ for 1..255; } warn time-$^T; " > 2
0.265625 at -e line 1.

$ perl -lne " $tri = substr $_, 0, 3; if( $tri > 255 ){ die }   END{warn  time-$^T; } "  2
0.359375 at -e line 1, <> line 2550.