Use this snippet to get the max out of your site speed samples

_setSiteSpeedSampleRate.js

/**
 * GOAL: Get the maximum allowed RUM data pushed into GA each day
 * Use this formula if you're < 1,000,000 Pageviews / Day
 * If you're > 1,000,000, disregard this whole thing as the GA auto samples at your capped 1%
 * About Page Speed: https://support.google.com/analytics/answer/1205784?hl=en
 * About _setSiteSpeedSampleRate: https://developers.google.com/analytics/devguides/collection/gajs/methods/gaJSApiBasicConfiguration#_gat.GA_Tracker_._setSiteSpeedSampleRate
 */

var AVERAGE_DAILY_PAGEVIEWS = 100000; // Replace with your Average Daily Pageviews from Google Analytics

// needs to be pushed before _trackPageview 
_gaq.push(['_setSiteSpeedSampleRate',
  AVERAGE_DAILY_PAGEVIEWS < 10000 ?
    100 : parseInt(((10000 / AVERAGE_DAILY_PAGEVIEWS) * 100), 10) // PUSH IT TO THE LIMIT
]);

siteSpeedSampleRate.js

/**
 * GOAL: Get the maximum allowed RUM data pushed into GA each day
 * Use this formula if you're < 1,000,000 Pageviews / Day
 * If you're > 1,000,000, disregard this whole thing as the GA auto samples at your capped 1%
 * About Page Speed: https://support.google.com/analytics/answer/1205784?hl=en
 * About siteSpeedSampleRate: https://developers.google.com/analytics/devguides/collection/analyticsjs/field-reference#siteSpeedSampleRate
 */

var AVERAGE_DAILY_PAGEVIEWS = 100000; // Replace with your Average Daily Pageviews from Google Analytics

ga('create', 'UA-XXXX-Y', {
	// siteSpeedSampleRate has to be set in create
	'siteSpeedSampleRate': AVERAGE_DAILY_PAGEVIEWS < 10000 ?
		100 : parseInt(((10000 / AVERAGE_DAILY_PAGEVIEWS) * 100), 10)
});