Maybe something a simple as this is all you need? This loads a dictionary into a hash as dataset, and can service 100,000 requests from each of 4 concurrent clients at a rate of ~40,000 requests per second.

Note: This is a cut-down version of a server that expects each client to make many requests via a persistent connections. If your clients would only make a single request for each connection, I'd use a thread pool architecture, but I expect the throughput to be at least as good.

#! perl -slw
use strict;
use threads ( stack_size => 4096 );
use IO::Socket;

use constant {
    SERVERIP => '127.0.0.1',
    SERVERPORT => 3000,
    MAXBUF => 4096,
};

sub s2S{
    my( $p, $h ) = sockaddr_in( $_[0] );
    $h = inet_ntoa( $h );
    "$h:$p";
}

my %DB :shared;
chomp, $DB{ $_ } = $. while <>;
close *ARGV;

my $lsn = IO::Socket::INET->new(
    LocalHost => SERVERIP, LocalPort => SERVERPORT, Reuse => 1, Listen
+ => SOMAXCONN
) or die $!;

print "Listening...";
while( my $client = $lsn->accept ) {
    async {
        while( 1 ) {
            $client->recv( my $in, MAXBUF );
            unless( length $in ) {
                print "Disconnected from ", s2S $client->peername;
                shutdown $client, 2;
                close $client;
                last;
            };
            print "Received $in from ", s2S $client->peername;
            my( $cmd, @args ) = split ' ', $in;
            if( $cmd eq 'FETCH' ) {
                $client->send( $DB{ $args[ 0 ] } );
            }
            else {
                $client->send( 'Bad command' );
            }
        }
    }->detach;
}

sleep 1e9;
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