Profiling this program:
use v6;
my $fh = open '/usr/share/dict/words';
for $fh.lines {
1;
}
gives http://moritz.faui2k3.org/tmp/profile-1411722954.70066.html#routines
Sort by exclusive time. The top entry, <anon> at src/gen/m-CORE.setting:8094
belongs to ListIter.reify, the second to GatherIter.reify, the third is ListIter.reify again. All three are part of the grand lazy list iteration scheme, and make up 63% of runtime, even though the top two "offenders" are already JITted.