High Memory Usage in Flag series
<p>Working with large data sets (50000+) for "flags" type of series I encountered huge memory usage leading to momentarily browser hanging and unresponsive webpage.</p>

<p><a href="http://jsfiddle.net/50zab8tc/14/" rel="nofollow">In this jsfiddle</a> there are 2 commented series, both with 10,000 values but one series type "line" and the other one type "flags", using Chrome's task manager you can see that the difference in memory usage between both is significant (10 MB vs 155 MB) (uncomment one series at a time, it can slow down your browser).</p>

<p>Here I leave the test code but with only 2 data values, the jsfiddle has 10,000.</p>

<pre><code>$(function () {
    $.getJSON('https://www.highcharts.com/samples/data/jsonp.php?filename=usdeur.json&amp;callback=?', function (data) {
        $('#container').highcharts('StockChart', {
            series: [
///*            
            {type: 'line',
                name: 'Line on series',
                turboThreshold: 0,
                data:[[1465241389],[1465242389]]
            }
//*/
/*
            {type: 'flags',
                name: 'Flags on series',
                turboThreshold: 0,
                data: [{x:1465241389,title:''},{x:1465242389,title:''}],                
                onSeries: '',
                shape: 'squarepin'
            }
*/          
        ]});
    });
});    
</code></pre>

<p>Looking at highstock src I noticed that in initSeries method a call to merge function is made. That function duplicates the series object including all it's DATA (10,000 values in the example), I don't know why it has to do this.</p>

<p>Is there a way to specify flags data with simple arrays? or a way to use over 50,000 flag values without the page hanging? </p>

<p>EDIT:</p>

<blockquote>
  <p>Here's the example using type "line": <a href="http://jsfiddle.net/vzf3vr2p/1/" rel="nofollow">http://jsfiddle.net/vzf3vr2p/1/</a>
  Here's the example using type "flags":<a href="http://jsfiddle.net/50zab8tc/15/" rel="nofollow">http://jsfiddle.net/50zab8tc/15/</a></p>
</blockquote>