G'day viffer,

If you declare %params earlier in your code, you can write:

        if ($server eq 'lsrch1') {
            my %params = map { $_ => 1 } @lsrch1;
            if(! exists($params{$string})) {
                push (@lsrch1, $string);
            }
        }
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as:

        if ($server eq 'lsrch1') {
            push @lsrch1, $string unless $params{$string}++;
        }
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You haven't shown the context of your code (which is fine); however, it leaves me in the dark as to advising where exactly to delare %params. Also, I don't know where $string comes from. Here's my test showing how my code might be implemented (adapt for your context as appropriate):

$ perl -Mstrict -Mwarnings -e '
    my @strings = qw{a a a b b c d d e e e};
    my $server = "lsrch1"; # Fudge for demo
    my @lsrch1;
    my %params;

    for my $string (@strings) {
        if ($server eq "lsrch1") {
            push @lsrch1, $string unless $params{$string}++;
        }
    }

    print "\@strings:     @strings\n";
    print "\%params keys: @{[sort keys %params]}\n";
    print "\@lsrch1:      @lsrch1\n";
'
@strings:     a a a b b c d d e e e
%params keys: a b c d e
@lsrch1:      a b c d e
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