Why page Load time 0 for most of the pages in GA?

Question

We are using google analytics in our application and getting strange results when tracking page load time. The data for most of the pages is 0 while few pages have the values. Now if we compare these pages with our qa sites , page load time has a value. Nothing has changed on these pages when we move to production except that we have a different tracking code and the application is available publicly. From screen shot below, you can see that we have data only for few days.

I am not sure what is happening here. Any pointers will be appreciated.

This is our code

<script type="text/javascript">
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
ga('create', "my-google-analytics-code", 'auto');
ga('send', 'pageview', {'page': (location.pathname+location.search+location.hash)});
</script>

Answer 1

Site speed is only tracked on 1% of visitors by default so it's likely nothing has been recorded yet for those pages, you can increase this by editing the ga('create' part of your code

ga('create', 'UA-XXXX-Y', {'siteSpeedSampleRate': 10})

https://developers.google.com/analytics/devguides/collection/analyticsjs/field-reference#siteSpeedSampleRate