On my machine it's the opposite. Join is faster. I tried several array sizes (sorted and unsorted arrays) with random numbers. I have Windows laptop with Activestate Perl build 819 (v5.8.8). 
Benchmark: timing 1000 iterations of join, md5...
      join: 46 wallclock secs (43.51 usr +  0.07 sys = 43.58 CPU) @ 22
+.95/s (n=1000)
       md5: 55 wallclock secs (53.15 usr +  0.03 sys = 53.18 CPU) @ 18
+.81/s (n=1000)

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In reply to Re^2: Fast way to check if a sort was doen by aku
in thread Fast way to check if a sort was doen by Outaspace

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