In case anyone's curious as to the actual benchmark results...

Time::Local is a 4400% speedup. I was expecting a lot, but that's a lot more than I expected.

It looks like regexp based timelocal_nocheck() is 3% faster than the unpack() version -- that could be because of my unnecessary assignment. Neat. I like that Benchmark module.

sub datemanip { &UnixDate(&ParseDate($date), '%s') }
sub r_timelocal    { $date =~ m/^([A-Z][a-z]{2}) (\d{2}) (\d{2}):(\d{2
+}):(\d{2})$/; timelocal($5, $4, $3, $2, $month{$1}, 2005) }
sub r_timelocal_nc { $date =~ m/^([A-Z][a-z]{2}) (\d{2}) (\d{2}):(\d{2
+}):(\d{2})$/; timelocal_nocheck($5, $4, $3, $2, $month{$1}, 20
sub u_timelocal_nc { my @a = reverse unpack('A3xA2xA2xA2xA2', $date); 
+$a[$#a] = $month{$a[$#a]}; timelocal_nocheck(@a, 2005); }

Date::Manip: 768 wallclock secs (636.70 usr +  3.83 sys = 640.53 CPU) 
+@ 156.12/s (n=100000)
r timelocal: 20 wallclock secs (14.86 usr +  0.10 sys = 14.96 CPU) @ 6
+684.49/s (n=100000)
r timelocal nc: 16 wallclock secs (14.40 usr +  0.06 sys = 14.46 CPU) 
+@ 6915.63/s (n=100000)
u timelocal nc: 20 wallclock secs (14.80 usr +  0.08 sys = 14.88 CPU) 
+@ 6720.43/s (n=100000)

                 Rate    Date::Manip   r timelocal u timelocal nc r ti
+melocal nc
Date::Manip     156/s             --          -98%           -98%     
+      -98%
r timelocal    6684/s          4182%            --            -1%     
+       -3%
u timelocal nc 6720/s          4205%            1%             --     
+       -3%
r timelocal nc 6916/s          4330%            3%             3%     
+        --
[download]