You might want to compare how these Benchmark: 
@foo{keys %bar} = values %bar;
%foo = (%foo, %bar);
foreach (keys %bar) { $foo{$_} = $bar{$_} }

[download]
You can speculate on what might be the fastest, but Benchmark can be one way to validate it. No benchmark is perfect, though, but it can at least give you an idea.

In reply to Re: Fast Way to Combine Two Hashes by tadman
in thread Fast Way to Combine Two Hashes by arunhorne

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