One reason it's so slow is that you're loading the entire database table into your program, when you only need 3 lines! You don't need to do that; since you're using MySQL, you can use the LIMIT directive:

    select foo from bar limit 3
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What do you want that where clause to do? That matches *any* ID: so you don' t need it. Just eliminate the where clause entirely.

And why are you selecting three columns if you only want one? Just say

    select data from frog limit 3
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Also you should try using bind_columns and fetch, cause it's faster:

    my($data);
    $sth->bind_columns(\$data);
    while ($sth->fetch) {
        print $data;
    }
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If you want to select multiple columns, try this:

    my $sth = $dbh->prepare(<<SQL);
select id, data from frog limit 3
SQL
    $sth->execute;

    my($id, $data);
    $sth->bind_columns(\$id, \$data);
    while ($sth->fetch) {
        print $id, "\t", $data, "\n";
    }
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(By the way, I took out the error-checking partly for brevity, and partly cause I always use RaiseError).

Check out Tricks with DBI.