First stab at timing harness, two example sequences.

bin/collatz-recursive.pl

@@ -0,0 +1,15 @@
+sub collatz-length(Int $n) {
+    given $n {
+        when 1 { 1 }
+        when * %% 2 { collatz-length($_ / 2) }
+        default { collatz-length(3 * $_ + 1) }
+    } 
+}
+
+sub MAIN(*@numbers) {
+    for @numbers -> $n {
+        say "$n: " ~ collatz-length($n.Int);
+    }
+}
+
+

bin/collatz-sequence.pl

@@ -0,0 +1,11 @@
+sub collatz-length(Int $start) { 
+    +($start, { when * %% 2 { $_ / 2 }; when * !%% 2 { 3 * $_ + 1 }; } ... 1);
+}
+
+sub MAIN(*@numbers) {
+    for @numbers -> $n {
+        say "$n: " ~ collatz-length($n.Int);
+    }
+}
+
+

bin/timing-harness.pl

@@ -0,0 +1,15 @@
+my $perl6 = @*ARGS.shift;
+my @numbers = 1..100, 10000..10100;
+
+my %results;
+for @*ARGS -> $script {
+    my $start = now;
+    qqx/$perl6 $script { @numbers }/;
+    my $end = now;
+
+    %results{$script} = $end - $start;
+}
+
+for %results.pairs.sort(*.value) -> (:key($script), :value($time)) {
+    say "$script: $time seconds";
+}