Clarification on User-Agent Handling

Hi team

I’ve been reviewing the Seraphinite Accelerator plugin and noticed that it includes logic for altering or “normalising” user-agents, including references to known testing and performance tools such as Chrome Lighthouse, GTmetrix, and others.

Could you please explain the purpose of this behaviour?

From my end, it looks like the plugin may be modifying or substituting the HTTP user-agent string before page generation, which could potentially cause different versions of the site to be served depending on who’s requesting it. I’d like to understand whether this is purely for cache segmentation and compatibility purposes, or if it’s intended to adjust what’s delivered to synthetic testing tools like Google PageSpeed or Pingdom.

I’m particularly interested in:
• What specific logic or benefit the “normalise user-agent” option provides.
• Whether the plugin ever serves a different or simplified HTML version to known performance test agents.
• How this approach complies with Google’s guidelines on cloaking and page-speed testing accuracy.

What caused me to look into your code is because I’m seeing a very large jump in Google PageSpeed scores when the plugin is active (from around 60 to nearly 100), yet Lighthouse in Chrome shows quite different results. Before I deploy this more widely, I just want to be confident that it isn’t optimising only for benchmarking tools rather than for real visitors.

Thanks in advance for clarifying this.