Faster Hash Slices

jht has asked for the wisdom of the Perl Monks concerning the following question:

I have a program that reads and processes approximately 8 million lines of data. For each line read it does:

my @aa = split(/\t/);
@{$ref}{@head} = @aa;
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When I measure the time spent, the:

@{$ref}{@head} = @aa;
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Seems to be fairly expensive time wise. Is there a better/faster way to accomplish this? Should I dump the hash and try something like this?

my ($field1,$field2,$field3, ... ,$fieldn) = @aa
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