Google Site Kit Dropped My PageSpeed by 40 Points. Here's What I Did.

I spent two weeks trying to push a client's mobile PageSpeed score above 40. Tweaked images. Minified CSS. Deferred every script I could find. The score barely moved. Then I deactivated Google Site Kit. The score jumped to 88. Two weeks of optimization work, undone by a single plugin that was supposed to help.

The PageSpeed drops users are reporting

Google Site Kit has 5 million active installs. A significant number of those users have reported PageSpeed drops on WordPress.org support forums, and the numbers are not subtle.

One user reported their score dropped from 86 to somewhere between 19 and 31 after activating Site Kit. That is a 55 to 67 point penalty from a single plugin. Another went from 94 to 47. A third saw their score go from 90 to 50 after installing it. Ed Rishel, a developer who wrote about the experience, documented a 40-point drop.

Documented drops from WordPress.org and Google's own support forums:

• 86 → 19 (67-point drop) -- levanii, WordPress.org
• ~50 points lost across multiple sites -- jomfruane, WordPress.org
• 94 → 47 (47-point drop) -- lianazaman, WordPress.org
• 90 → 50 (40-point drop) -- Google AdSense Community
• +22 points recovered after deactivating -- boionfire81, WordPress.org

These are not outliers buried in one forum thread. Site Kit has 143 one-star reviews (14.6% of all reviews) on WordPress.org, and performance is one of the most common complaints. One reviewer reported LCP rising from 2.4 to 8.4 seconds after turning Site Kit on. Another said the site was "waiting forever for googleads.doubleclick.net" even though they did not use Google Ads.

If you are wondering whether your PageSpeed problems are caused by Site Kit, here is the fastest way to check: deactivate it. Run PageSpeed Insights. Compare the scores. Multiple users report seeing a 20+ point improvement within seconds of deactivating. If that is your experience, keep reading. There is a way to get your analytics data without the performance cost.

What Site Kit actually loads on your site

Google's official documentation claims Site Kit itself "only inserts a meta tag on the front-end." That is technically true in the narrowest possible sense. Site Kit inserts the meta tag. Then it inserts GA4's gtag.js script, which weighs 134 KB compressed and 371 KB uncompressed. That is 6.7 times larger than the old Universal Analytics script.

If you have connected AdSense, Tag Manager, or Consent Mode, Site Kit loads those scripts too. One user documented that Site Kit was loading four Google JavaScript files totaling over 419 KiB on their homepage: Google Ads scripts (196 KiB + 52 KiB), Google Tag Manager (109 KiB), and a consent provider script (62 KiB).

On the server side, Site Kit loads its PHP framework on every single page request. Not just admin pages. Every page. The Plugin::register() method fires at WordPress init priority -999 and initializes roughly 30 subsystems: Authentication, Modules, Permissions, Assets, REST API routes, and more. For visitors who will never see any of this, it still runs.

For comparison, if you paste the GA4 snippet manually, you get the same gtag.js script on the frontend but zero PHP overhead on the server. No 1.13 MiB of memory. No 30 subsystems initializing on every request. No REST API routes registered for a dashboard your visitors will never see.

The PHP overhead Google does not mention

PluginTests.com tracks Site Kit's server-side footprint across versions. The trend is not encouraging:

Memory usage has grown 42% across these versions. The page generation penalty has roughly doubled. And this is just the passive cost of having the plugin installed. It gets worse under specific conditions.

In December 2020, a developer running a site with 10 million monthly pageviews filed a GitHub issue documenting 20-second page loads. The cause: Site Kit was making synchronous API calls to Google's servers during page generation for logged-in users. Pages that normally loaded in under 0.5 seconds randomly took 10 to 20+ seconds. The server had four AMD EPYC processors and 64 GB of RAM. It did not matter.

In January 2025, a P0 bug caused Site Kit to crash WordPress dashboards on sites running New Relic Browser Agent. A conflict between the two triggered an infinite loop in Site Kit's notification code, consuming all available memory. A separate out-of-memory issue from December 2024 remains open and unresolved.

On the frontend optimization side, a GitHub issue proposing to reduce Site Kit's 2.7 MB vendor bundle by removing 21 unused npm dependencies has been open since December 2021. Over four years, no action taken.

PageSpeed is not a vanity metric

A 40-point PageSpeed drop is not just an orange number turning red. It is a measurable loss in traffic and revenue.

Google's own research found that 53% of mobile visitors leave a page that takes longer than 3 seconds to load. As load time increases from 1 to 5 seconds, bounce probability increases by 90%. Amazon's internal testing found that every 100ms of added latency cost 1% in sales. Vodafone ran an A/B test and found that a 31% LCP improvement led to 8% more sales.

Core Web Vitals are a Google ranking signal. They have been since June 2021. And only 40% of WordPress sites on mobile pass all three Core Web Vitals metrics, compared to 57% for Wix and 56% for Drupal. WordPress already has a performance disadvantage. Adding Site Kit makes it worse.

Alex Russell, a performance engineer at Microsoft who previously worked on Chrome, has written that building websites to the limits of high-end hardware is "active malpractice." Addy Osmani, from Google's Chrome team, recommends a JavaScript budget of less than 170 KB compressed for mobile. GA4's gtag.js alone blows through 79% of that budget before your site loads a single line of its own code.

If your analytics plugin is the thing keeping your site from passing Core Web Vitals, the plugin is costing you traffic.

The irony: Site Kit measures the speed it hurts

Google makes PageSpeed a ranking factor. Google builds a plugin that hurts PageSpeed. Google's PageSpeed tool flags Google's own plugin as the problem. The user in between gets a lower score, less traffic, and a suggestion to optimize the scripts that Google put there.

This is not a new observation. Per Karlsson from BKWine tested Site Kit before and after with GTmetrix and wrote: "Very ironic since Google is the big champion of fast pages and even uses it as a ranking factor in searches. Well, obviously they are not following their own advice."

The fix should be straightforward. In May 2025, Weston Ruter, a WordPress core contributor, filed an issue on the Site Kit repository proposing three changes: add fetchpriority="low" to the gtag script, move it from the head to the footer, and remove the unnecessary DNS prefetch for googletagmanager.com. He even built a prototype plugin demonstrating the fix.

The Site Kit maintainer's response in October 2025: "Thanks for the bump, I'll raise this with the team." As of March 2026, the issue is still open. No fix shipped.

The consent banner tax

Site Kit's performance cost does not stop at the analytics script. Because Site Kit loads Google Analytics, and Google Analytics sets cookies (_ga, _ga_<container-id>), you need a cookie consent banner in the EU. That consent banner adds its own JavaScript to the page.

Popular consent management platforms add significant JavaScript overhead. OneTrust, for example, adds 124 to 347 KB depending on configuration. So the real performance cost of Site Kit in the EU is not just gtag.js. It is gtag.js (134 KB) plus the consent banner (50-200 KB) plus whatever other Google services you have connected. You can easily exceed 300 KB of tracking and consent JavaScript before your site loads its first image.

And here is the kicker: over half of EU visitors reject cookies when given equal-prominence Accept and Reject buttons (etracker 2024 data). In Germany and France, the rejection rate is even higher. Every visitor who rejects is invisible to Google Analytics. You slowed your site down for everyone, and you are only tracking the minority who clicked Accept.

Google's own GDPR approach makes this worse. The community asked for built-in consent management in August 2019. After 22 comments over nearly five years, Google closed the issue as "Not Planned" in May 2024. To make Site Kit GDPR-compliant, you need three plugins working together: Site Kit, the WP Consent API bridge, and a third-party consent platform. Each one adds PHP overhead. Each one adds JavaScript. Each one is another thing that can break.

Cookieless analytics that do not set cookies, do not collect personal data, and do not require consent banners eliminate this entire layer of complexity and performance cost.

Three options for fixing the problem

If Site Kit is hurting your PageSpeed, you have three paths forward.

Option A: Remove Site Kit, paste the GA4 code manually

Copy the gtag.js snippet from your GA4 property. Paste it using WPCode (free plugin, 2 million installs). You keep everything GA4 offers, including Enhanced Measurement for outbound clicks, file downloads, scroll depth, and site search. The only difference is checking analytics.google.com instead of your WordPress dashboard.

One WordPress.org user reported a 22-point PageSpeed improvement from this exact switch. The frontend JavaScript is the same, but you eliminate the PHP overhead entirely.

The downside: you still have GA4's 134 KB script on every page, you still need a cookie consent banner in the EU, and you still lose the majority of European visitors who reject cookies.

Option B: Delay the GA4 scripts with a caching plugin

WP Rocket's Delay JavaScript Execution prevents all JavaScript from loading until a user interacts with the page (mouse movement, scroll, click). This dramatically improves PageSpeed scores. WP Rocket has built-in exclusion checkboxes for Google Analytics and Tag Manager.

The catch: when JavaScript is delayed, GA4 does not load or fire until the first interaction. Visitors who land, read your content, and leave without moving their mouse are completely invisible. You get a better PageSpeed score but worse analytics data. You are trading one problem for another.

Option C: Replace the whole stack

Replace both Site Kit and Google Analytics with a standalone analytics tool that does not require a WordPress plugin, does not load Google's scripts, and does not need a consent banner.

This is what Clickport does. One script tag. No WordPress plugin. No Google dependency. No cookies. No consent banner. The tracking script is 1.9 KB gzipped, which is 70 times smaller than GA4's 134 KB payload. Because there is no WordPress plugin, the PHP overhead is zero. Because there are no cookies, the consent banner is unnecessary.

What is your analytics costing you?

Use this calculator to estimate how much traffic and revenue your analytics setup may be costing. Enter your numbers and see the impact.

What a 1.9 KB tracker looks like

The performance difference between a 134 KB analytics script and a 1.9 KB one is not abstract. It is a concrete reduction in network requests, main thread blocking time, and time to interactive.

Clickport tracks scroll depth, outbound links, file downloads, form submissions, 404 errors, internal search terms, and copy detection automatically. It has goal tracking with revenue attribution, cross-filtering, annotations, a world map, and CSV/PDF exports. It works on WordPress, Shopify, Next.js, static sites, anything with HTML.

The installation is one line of code in your theme header. Data appears in real-time within seconds. No Google account to connect. No OAuth tokens that expire. No "Gathering data" screen that lasts forever. No conflicts with your caching plugin, your security plugin, or your page builder.

Start your free 30-day trial. One script tag. Real-time data in 60 seconds. No plugin, no cookies, no consent banner.

What you lose by removing Site Kit

In the interest of honesty: Site Kit does provide genuine convenience for people who want Search Console data, Analytics data, and PageSpeed data inside their WordPress dashboard without visiting three separate Google properties. If you check those dashboards daily and strongly prefer not to open a browser tab, Site Kit saves you a few clicks.

That is the complete list of what you lose. Every data point Site Kit shows is available at analytics.google.com and search.google.com/search-console. Site Kit adds no unique data of its own. If you uninstall it, GA4 keeps every pageview, session, and conversion.

You also lose some things you probably did not want in the first place: the PHP overhead, the plugin conflicts with Wordfence, Elementor, and WPML. The OAuth disconnections that happen almost daily for some users. The multisite support that took nearly seven years to ship after being requested in 2019.

If you need analytics that work without a plugin, without consent banners, without performance penalties, and without a Google dependency, Clickport does that. 30-day free trial. No credit card required. Two minutes to set up.

FAQ

Does Google Site Kit slow down WordPress?

Yes. Users on WordPress.org report PageSpeed drops of 20 to 67 points after installing Site Kit. The plugin adds 1.13 MiB of PHP memory on every page request and loads GA4's 134 KB gtag.js script on the frontend. Google's official documentation acknowledges "a slight impact on performance" from the network requests.

How many PageSpeed points does Site Kit cost?

It varies by configuration. With just Analytics connected, users report 11 to 22 point drops. With Analytics plus AdSense, drops of 40 to 67 points are documented. The worst reported case is a score dropping from 86 to 19.

Can I use Site Kit without Google Analytics?

Yes. You can connect only Search Console and PageSpeed Insights. In that configuration, Site Kit adds only a meta tag to the frontend and does not load gtag.js. However, the PHP backend overhead remains.

Does removing Site Kit delete my analytics data?

No. Your data lives on Google's servers. Uninstalling Site Kit has no effect on your GA4 data. You can still access everything at analytics.google.com.

Is Site Kit safe to use?

Site Kit had one security vulnerability (CVE-2020-8934), a privilege escalation bug that allowed subscriber-level users to gain Search Console owner access. It was patched in v1.8.0. More broadly, every WordPress plugin increases attack surface. 96% of WordPress vulnerabilities come from plugins. A script tag cannot introduce PHP-level vulnerabilities.

What is the lightest WordPress analytics option?

If you want to stay with Google Analytics, paste the GA4 snippet manually using WPCode instead of Site Kit. If you want to eliminate the GA4 overhead entirely, lightweight standalone trackers like Clickport (1.9 KB gzipped), Plausible (1.3 KB), and Fathom (2.0 KB) are 65 to 100 times smaller than GA4's 134 KB payload.

Does Site Kit support WordPress Multisite?

Site Kit only added multisite support in March 2026, nearly seven years after the feature was first requested in July 2019. Earlier versions had no multisite support and network-activating the plugin was reported to break user registration.

Will removing Site Kit improve my Core Web Vitals?

Removing Site Kit eliminates the PHP overhead. If you also remove GA4 (or replace it with a lightweight tracker), you remove 134 KB of JavaScript from every page load. This directly improves Largest Contentful Paint (LCP) and Total Blocking Time (TBT), two of the three Core Web Vitals metrics.