Zendesk: impact on page speed
Category: Chat widget
The Zendesk Web Widget loads chat and help-centre features into the page at startup. Like other chat widgets it costs main-thread time on every page view, not only for visitors who use it.
On 1.0 % of the 4108 homepages measured, Zendesk is among the five heaviest third parties. Where it is, it takes a median of 249 ms of main-thread time; on the heaviest quarter of those sites it takes 302 ms or more.
1.0 %
of homepages: among the five heaviest third parties
249 ms
median main-thread time
302 ms
main-thread time on the heaviest quarter (p75)
412 KB
median transfer size
Distribution across homepages
Percentiles across 40 homepages with Zendesk.
| Percentile | Main-thread time | Transfer size |
|---|---|---|
| p25 |
202 ms
|
393 KB |
| Median |
249 ms
|
412 KB |
| p75 |
302 ms
|
414 KB |
| p90 |
381 ms
|
476 KB |
In context
By median main-thread time, Zendesk ranks ninth of 65 third parties in the benchmark, lighter than Facebook and heavier than Klaviyo.
On 50 % of the homepages where it appears, Zendesk alone uses 250 milliseconds of main-thread time or more, the mark from which Lighthouse flags third-party code.
Homepages with Zendesk weigh 5.5 MB at the median (JavaScript: 2.3 MB), homepages without it 4.3 MB (JavaScript: 1.6 MB).
Often loaded together with
Share of homepages with Zendesk where the other tool is also among the five heaviest third parties.
- Google Tag Manager 68 %
- Facebook 33 %
- Google CDN 20 %
How to spot Zendesk on your page
The widget loads snippet.js from static.zdassets.com, then around a dozen widget modules from the same host and its configuration from the account's own zendesk.com subdomain. Many sites load it globally even though support requests come almost exclusively from the help and order pages. Moving the widget behind a facade keeps it one click away without charging every visitor for it.
How to reduce the impact of Zendesk
- Load the widget on click through a facade button.
- Limit the widget to help and contact pages.
- Disable widget features you do not use in the Zendesk admin.
Frequently asked questions
How can I load Zendesk with less impact?
Load the widget on click through a facade button. Limit the widget to help and contact pages.
Does Zendesk affect Core Web Vitals?
The Zendesk widget mostly costs INP. It loads its web widget framework on page load so that chat or help center search is ready immediately, even though most visitors never open it. The launcher floats above the page, while contact forms or answer bots placed in the page flow can add layout shifts.
Method and sample: Third-Party Benchmark.