Hash look-ups will probably speed things up:

use warnings;
use strict;

my @taxR = ("PLRV1", "PMTVS", "PVXHB");
my %taxRh = map { $_ => 1 } @taxR;
my $curEntry = "PMTVS";
if (exists $taxRh{$curEntry}) {
    print "do rest of stuff";
}
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