Regex alternation is costly and somewhat crufty.

Building a hash works, but I'd prefer to at least do it non-iteratively:

my %stop;
@stop{qw(first second third)} = ();
next if exists $stop{$field};
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Personally, I'd use the following: next if grep $field eq $_, qw(first second third); grep in scalar context returns the number of matches.

Makeshifts last the longest.