I would try doing this:

my $sqlString = 'delete from %s;';

$dbh->begin_work;
my @tables = ('table1','table2','table3');
foreach my $table (@tables) {
    my $sth = sprintf($sqlString, $table);
    $dbh->do( $dth );
}
$dbh->commit;
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This would speed it up some, but double-check the DBI doco on cpan for the 'begin_work' function before you do it on how it will react since I think it depends on the database you use and whether it supports transactions or not.

The last thing you could try could be a drop/create where you basically drop the old table and re-create it from scratch... That will definately speed it up, but some people get twitchy when doing it :)
Something like

$dth->do("drop table0");
$dth->do("create table0 ( col1 def, col2 def.....)");
etc....
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