Efficient for what? Speed or maintainability? Assigning a reference is pretty low cost and lexical variables are slightly more efficient. It's probably much of a muchness either way but you should benchmark if you need to know.

use Benchmark;

cmpthese ( -1, {
    local => sub { ... },
    value => sub { ... },
);
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Personally I'd use lexical variables and if copying was expensive or I wanted to modify the arguments use $_[0] etc or Data::Alias if I refer to an argument more than once or need to document it's purpose. For example

use Data::Alias;

sub sample {
    alias $html = $_[0];
    ...
}
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