Node-Mysql database query + res.json far too slow

I am learning Node.

Using Express and Node-Mysql, I am successfully able to query my mysql database and return the result to the client as JSON.

However, it is far too slow. For a simple query with a LIMIT of 100 it is taking about 6 seconds to get the response.

According to my logger, the DB query only takes about 8 ms to run - so I do not think that node-mysql is the problem.

But the only other thing I am doing is passing the resultset to the response object to be converted into json.

Here is my code, roughly:

Route:

app.get( "/exercises", function( req, res ){
    exercises.get( req.query, function( result ){
        res.json( result );
    });
});

Model:

module.exports.get = function( params, cb ){
    var sql = "SELECT * FROM exercises LIMIT 100";
    db.do( sql, function( result ){
        var response = {};
        response.data = result[ 0 ];
        response.meta = result[ 1 ][ 0 ];
        cb( response );
    });
};

DB:

module.exports.do = function( sql, vals, cb ){
    var selectStart = +new Date();
    pool.acquire(function( err, db ){
        db.query( sql, vals, function( err, result ) {
            cb( result );
            console.log( "Query Execuction: %d ms", +new Date() - selectStart );
            pool.release( db );
        });
    });
};

Does anyone know what I could be doing wrong / why it is taking so long to send the resultset to the client?

Thanks (in advance) for your help.