What is CLS by UTM Source
CLS by UTM Source shows Cumulative Layout Shift (CLS) values across different UTM sources (e.g., newsletter_april). This lens helps you identify whether specific marketing campaigns or traffic sources are delivering a visually unstable experience to users.
The list includes only UTM sources that generated traffic to your site during the selected period.
Unexpected layout shifts can vary depending on how landing pages are structured or how third-party scripts behave for certain campaign audiences.
Healthy CLS by UTM Source sample
A healthy CLS by UTM source lens shows all green — meaning users coming from different campaigns or sources are experiencing a stable, polished layout.
Some UTM sources may perform slightly better than others, but as long as none are yellow or red, your campaign traffic is in good shape.
Unhealthy CLS by UTM Source sample
In the example here, traffic from RevOffers has the highest CLS — even though it’s one of the most active UTM sources.
This could be caused by:
Campaign-specific banners or modals loading late.
Personalization scripts triggered only for specific UTM parameters.
Landing page variants with unreserved space for images, forms, or content blocks.
High CLS for campaign traffic can lead to reduced trust, higher bounce rates, and underperforming conversion metrics.
Resolving unhealthy CLS by UTM Source
Go-to action plan to resolve an unhealthy CLS by UTM Source:
Ask Uxi to analyze your CLS by UTM Source values and suggest improvements
Use Filters to isolate slow-performing campaign segments, then cross-check with other lenses like page, device, or user type.
Simulate CLS of the suspected lens to see if fixing it will resolve the CLS by UTM Source. If yes, this is where the resolution focus should be.
Use an automated CLS optimization tool like Navigation AI to improve your CLS by UTM Source values
Once you’ve improved CLS, set an alert to be the first to know if it starts worsening again.
Try it yourself
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