Google Analytics provides a variety of tools to help you better understand your website, its traffic, and its user experience quality. While it perhaps is not its most used feature, Google Analytics can provide you with Site Speed Reports that list your various pages’ load times.
To do this, Google uses a sampling of the overall sessions on your page, and you have the ability to customize the precision of these samplings. The report will provide you with average load times, average redirect times broken down by browser type, page download times, and server response times.
You want to make sure to keep your mobile audience in mind while optimizing your site speeds, and your Site Speed Reports can help you do this as well. Take a look at Pageviews in your Page Timings Report and select the Charting option, located to the far left. This will allow you to view mobile devices as your Secondary dimension, giving you an idea of what parts of your site are loading slowly on mobile.
Google also gives you the option of viewing a Speed Suggestions Report, which advises you on steps to take to improve your site’s speed. As speed is an important factor in determining the quality of a user’s experience on your site, take advantage of all that Google offers to help improve it.