Note that CPUs (these days) support conditional instructions; good compilers make use of these. Loop body such as

    if (v[i] >= 128)
        sum += v[i];
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is likely compiled with a cmov on x86/x86_64 and therefore incurs no branch misprediction penalty.

As for the perl version: the effects of misprediction are practically negligible, lost in the noise.

perf stat perl5.18.1 -e '@a = map {($i += 1.1e-0) + rand} 1..3e6; $i =
+ $i/2 + 0.5; $_ > $i and $n+=$_ for @a;'
        8509781489 instructions
        1701278883 branches
           3938702 branch-misses
       1.561091272 seconds time elapsed

perf stat perl5.18.1 -e '@a = map {($i += 1.1e-10) + rand} 1..3e6; $i 
+= $i/2 + 0.5; $_ > $i and $n+=$_ for @a;'
        8505802267 instructions
        1700634854 branches
           5437641 branch-misses
       1.567880931 seconds time elapsed
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