What is PLS by UTM Source
PLS by UTM Source lens breaks down Perceived Load Speed (PLS) by the source of your traffic, based on the utm_source parameter in your campaign URLs (e.g. google, facebook, newsletter, etc.). This lens helps you understand if certain traffic channels consistently deliver a better or worse perceived load experience.
Different UTM sources often imply different devices, network types, or user behaviors. For example, visitors from a “newsletter” campaign may open your site in a desktop email client, while “facebook” traffic might lean mobile and slower connections. These variations affect how fast your site feels across segments — which is exactly what PLS captures.
Healthy PLS by UTM Source sample
Should you worry
A healthy PLS by UTM source lens shows relatively consistent performance across the board, with no major outliers. It’s okay if some sources (like paid ads or organic) perform slightly better due to higher-intent users or cleaner landing pages — but large gaps between sources may signal issues worth fixing.
If a high-traffic or high-converting source (like google or a key newsletter) shows poor PLS, it’s worth investigating. These users are already interested — slow loading can ruin that momentum.
Unhealthy PLS by UTM Source sample
When this lens is unhealthy, one or more UTM sources stand out with significantly worse perceived load speed. This can result from poorly optimized landing pages, overloaded tracking scripts, or untested experiences in that campaign’s primary environment (e.g. Android Facebook app browser).
If slower PLS aligns with high bounce or exit rates from that UTM source, it may be directly costing you performance-driven conversions.
Resolving unhealthy PLS by UTM Source
Go-to action plan to resolve an unhealthy PLS by UTM Source:
Ask Uxi to analyze your PLS by UTM Source and suggest improvements.
Use Filters to isolate sessions from problematic sources and analyze their device, browser, and location trends.
Simulate LCP of the suspected lens to see if fixing it will resolve the PLS by UTM Source. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your PLS by UTM Source.
Once you’ve improved PLS, set an alert to be the first to know if it starts worsening again.
Try it yourself
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