gistfile1.js

var z = +new Date();

for( var j = 0; j < 100; j++ ){
    var elements = [];

    for( var i = 0; i < 1000; i++ )
        elements.push(
                <div key={i} className="row">
                    <div className="col">a</div>
                    <div className="col">b</div>
                    <div className="col">c</div>
                </div>
        );

    React.render( <div> { elements } </div>, document.getElementById( 'perf-1' ) );
}

console.log( new Date() - z );