Your app's performance is one of the most important aspects of whether or not your business will succeed. According to Google's research, 29% of mobile users will avoid using a site or an application if it's too slow or too difficult to find information, with 70% of that user group doing so because the site is too slow. Diagnosing and fixing performance issues for your site or application helps your organization attract new users while retaining existing ones, and New Relic is just the tool to help you do it.

Diagnosing latency issues

First, you should familiarize yourself with the causes of high latency among most websites and applications. Knowing these can help you determine what the cause of high latency is for your own system. The most common types of high latency are:

When a user attempts to access a website and pages take longer than expected to load, this is often what causes the latency that the user is exposed to. You can diagnose this is a cause of latency using Largest contentful paint (LCP), one of Google's core web vitals. LCP is listed on the Summary page of , and you can also use the Session trace page of a browser monitor to identify specific causes of latency on a specific page.

When a user has to wait longer than expected to be able to interact with page elements, such as using search functions or using features, this is the cause of the latency that the user experiences. You can use First input delay (FID), another one of Google's core web vitals. FID is listed on the Summary page of , and the Session trace page of a browser monitor can help identify the specific cause of latency on a page.

When a user is feels that the overall performance of a site or application is poor, this is often the issue causing high latency. This can be caused by a number of factors, such as slow application times or long running JavaScript, but New Relic can help you find out if this is the issue your service is experiencing. AJAX monitoring is found on the Ajax page in . For more information, see our AJAX doc.

Once you know what the common causes of latency are and where to go to find them, you can use the Summary and Ajax pages in to find the cause of your high latency. You don't necessarily need to know how the services should perform overall, you only need to look for major recent changes in behavior.

An example of diagnosing high latency

Once you're familiar with the common causes of latency, you can narrow down the specific issue that is impacting your site. Let's take a look at a service that is having issues with latency.

Here, you see the Summary page for a service showing a Largest Contentful Paint of 8.44 seconds. Since everything else falls under acceptable parameters, you can narrow down the cause of your latency as slow page load. You could select Session trace page for a specific view of what might be causing the issues with your LCP. This would be a good place to start a search to find what is causing your latency issues.

You could also select the Largest Contentful Paint section itself to go to the Web vitals page for a more generalized overview of errors based on page URLs, device type, browser type, and more. Once you find the source of the issue using this method, you can repair the problem and get your user experience back to the levels that keep your customers happy.

Learn more about core web vitals

⬅️ PREVIOUS

See how to reduce JavaScript errors

NEXT ➡️

Fix your app's high latency

Diagnosing latency issues

Slow page load

Page non-interactivity

Slow AJAX requests

An example of diagnosing high latency

Learn more about core web vitals

See how to reduce JavaScript errors