# 10 fields..
while(read $fh, my $buffer, 128*2**10) {
   $buffer .= <$fh>;
   $buffer =~ s/\n/\|/g;
   my @in_field_heap = split /\|/, $buffer;

   while(my @field = splice @in_field_heap, 0, 10) {
       # ...
   }
}