What is CLS by CPU performance
CLS by CPU performance shows how Cumulative Layout Shift (CLS) varies depending on the estimated performance tier of the user's device CPU.
We group devices into:
High tier – Modern desktops, flagship phones, and powerful laptops
Mid tier – Average smartphones and older laptops
Low tier – Budget devices with limited processing power
This lens helps you understand how layout stability holds up across devices — especially when rendering resources are constrained.
Healthy CLS by CPU performance sample
A healthy distribution means:
All tiers — including low-end — maintain low CLS
Layouts are stable even when rendering takes longer
No unexpected shifts caused by late-loaded components or blocking scripts
This shows your site is resilient under pressure, keeping the user experience smooth regardless of CPU power.
Unhealthy CLS by CPU performance sample
If mid or low tier devices show high CLS:
Scripts may delay layout completion, letting elements shift after rendering starts
Lazy-loaded content (like images or banners) appears too late, moving content below
CPU constraints lead to delayed calculations of layout space or styles
If even high tier users experience layout shifts:
There may be fundamental issues in template structure or component behavior
Layouts aren’t reserving proper space for async content like ads, fonts, or carousels
This results in jarring visual shifts — a major UX hit on any device.
Resolving unhealthy CLS by CPU performance
Go-to action plan to resolve an unhealthy CLS by CPU performance:
Ask Uxi to analyze your CLS by CPU performance values and suggest improvements
Use Filters to isolate problematic pages or components on low/mid CPUs
Simulate CLS of the suspected lens to see if fixing it will resolve the CLS by CPU performance. If yes, this is where the resolution focus should be.
Use an automated CLS optimization tool like Navigation AI to improve your CLS by CPU performance values
Once you’ve improved CLS, set an alert to be the first to know if it starts worsening again.
Try it yourself
Discover how your website performs with real user data.