As developers, we often obsess over Lighthouse scores in a controlled environment. We tweak, we purge, and we run localhost audits until we see 100. However, as we all know, a controlled environment rarely reflects the chaos of the open web, which includes varying device speeds, flaky mobile networks, and heavy third-party scripts.
That is why the HTTP Archive Core Web Vitals Technology Report is such a great dataset. It ignores the lab tests and focuses entirely on Origin Data - real-world user metrics collected from millions of sessions.
I took a dive into the latest report to see how the major WordPress optimization plugins compare when subjected to real user traffic. The lineup included the usual heavy hitters: WP Rocket, LiteSpeed, NitroPack, FlyingPress, W3 Total Cache, and FastPixel.
Here is what the data tells us about the current state of WordPress performance.
The "Pass Rate" Metric
The most holistic metric in the report is the overall Core Web Vitals (CWV) pass rate, meaning a site passes LCP, CLS, and INP simultaneously.
The data showed a distinct split. While many competitors hovered in the mid-to-high 50% range (with some popular options falling below 50%), FastPixel hit a 60% pass rate.
For developers, this is significant. It suggests that a "less is more" approach—focusing on safe defaults rather than aggressive HTML rewriting, yields more consistent green scores across a diverse user base.
The New Boss: INP (Interaction to Next Paint)
Since INP replaced FID, interactivity has become the primary headache for many WordPress devs. It’s no longer enough to load fast; the main thread has to stay free.
The report highlights that staying "lean" is the only way to win here. FastPixel tied for the top spot (alongside W3TC and NitroPack) with an 86% good INP score. This reinforces the idea that if a plugin injects too much of its own logic to force a high LCP, it often hurts INP by clogging the main thread during interaction.
The Bloat Problem: Page Weight & JS
This was perhaps the most damning part of the report regarding the ecosystem as a whole.
When analyzing Page Weight, the trend line for most optimization plugins sits around 2MB or is actively climbing. In contrast, the data shows FastPixel consistently delivering payloads under 1MB.
The JavaScript footprint tells the same story. Many optimization plugins paradoxically add JS to the page to manage lazy loading, delay scripts, or handle warmups. The HTTP Archive data shows a clear hierarchy, with FastPixel maintaining the lowest JS weight, while others (specifically W3 Total Cache and FlyingPress) showed a trend of increasing script weight over time.
Why does this matter?
Many plugins try to "hack" performance by rewriting the DOM, injecting placeholders, and using heavy JS to trick the browser into prioritizing content. While this works in Lighthouse, the field data suggests it creates volatility for real users.
The approach that seems to be winning in the field is simpler:
- Aggressive image optimization.
- Serving as much as possible from the CDN.
- Keeping the plugin code itself virtually invisible on the frontend.
If you are currently battling with Core Web Vitals, it might be time to look at your optimization plugin's "weight".
If the tool meant to speed up your site is adding 500KB of JS to it, you might be fighting a losing battle.
Check out the full breakdown in the report to see the graphs for yourself.
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