How to measure the latency of third-party ads?

Written by Roy
May 17, 2021 • 3 min read

As a publisher, you want to be sure ads load fast enough, without slowing down the page. In today's programmatic world, every party in the ad tech stack adds their own libraries, pixels and ad validation scripts to a creative.

How are you going to measure the all of this added latency?

What is latency?

First of all, let's define latency as the time it takes for a data packet to be send across a network. In real life, this translates to the visible delay between the loading of a page and the moment something is painted on the screen.

Measuring load speeds

To measure the load speed of a creative, you can add the ad tag or HTML5 ad to a test page and look in Chrome Dev Tools at the DOMContentLoaded event. Upper thresholds are arbitrary, but aim for a load speed of < 500ms. The faster the better.

Also check the Console tab to see if document.write() is invoked. Some ad tech vendors are still using old techniques from the 90s.

Minification, CDN and image compression

A lot of the suggestions offered by Google's web essentials page can also be applied to ads. The JavaScript code to build the ad unit can be minified and gzipped. The assets themselves like images and videos can be hosted on a CDN to minimize network latency between the server and the user. Images can be compressed using lossless techniques to reduce their file size. Any self-respected ad server vendor should implement these techniques to keep latency at a minimum.

Ad Validation Tool for HTML5 Ads

You can use this HTML5 ad validation tool to scan a creative and see if your ad complies with your specifications. It measures a couple of things that Ad Ops check manually when validating ads before they go live.

HTML5 Ad Validation Test Tool (

Automated Creative QA via an API

If scanning each creative takes too much time, why not automate the whole QA process? Ask the development team within your company to integrate the APIs of in your platform. Each time you receive a new creative, you'll see within seconds if it passed all QA tests, right from your own portal.

Imagine the amount of time you would save on a yearly basis.


IAB Advertising Guidelines

The Interactive Advertising Bureau has guidelines regarding the performance of HTML5 ads created with Google Web Designer or any other rich media builder. You can find them in this PDF.


Creative quality assurance is an important process to validate ads before they go live. As a publisher, you want to be sure ads are loading fast, secure and without flaws. Automated ad validation tools can help Ad Ops to save valuable time and make the QA process less boring.

External Resources