In March 2025, Google rolled out one of its most significant Core Updates in recent years. While it continues to emphasise content quality, it also strengthens a broader trend: overall user experience is now a critical success factor for SEO.
At the heart of that experience is web performance — a crucial, yet often underestimated, lever. At Fasterize, the software provider behind the EdgeSpeed solution, we explain why optimising your site speed is no longer optional. It’s a necessity for safeguarding your visibility in the wake of this Core Update.
Of course, quality content remains the number one priority in any major Google update. Web performance doesn’t replace this requirement — it enhances its impact by improving the user experience and behavioural signals.
User Experience at the Core of SEO in 2025
For several years now, Google has made it clear that it aims to “reward helpful and reliable content that delivers a good user experience.”
The March 2025 Core Update takes that even further:
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User satisfaction: Relevant content is no longer enough if the user experience is poor.
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Behavioural signals: Time on page, bounce rate, and returns to the search results page are indirect signals now taken into account.
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Mobile experience and accessibility: Mobile performance has become business-critical.
In this context, even top-tier content may be penalised if it’s delivered through a slow, unstable, or frustrating interface.
Why Web Performance drives SEO post-Core Update
Improving your web performance isn’t just about technical scores — it’s about improving the real-world experience of your visitors, which in turn directly influences your SEO. Here’s how:
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Loading speed (strong LCP): Faster pages lead to longer user sessions.
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Responsiveness (optimised INP): Quick interactions foster engagement.
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Visual stability (low CLS): Prevents layout shifts and builds user trust.
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Reduced server response time (low TTFB): Enables faster indexing and more efficient crawling by Googlebot.
These metrics, known as the Core Web Vitals, can be tracked via CrUX. Your objective: keep them all in the green — not just for your domain, but across your key page types.
In short: Strong Web Performance drives positive behavioural signals, now tightly linked to your SEO results.
Focus : Web Performance et Crawl Budget Optimisation
Beyond UX, web performance directly impacts your crawl budget — a crucial but often overlooked SEO factor.
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Faster servers respond better to Googlebot requests.
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Slow-loading pages may be only partially crawled or delayed, slowing down their indexation.
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Reducing TTFB and ensuring a seamless experience helps bots explore your site more efficiently.
The result? In a post-Core Update landscape where Google is reassessing content at scale, a high-performing site gets crawled more effectively, refreshed more frequently, and ranked more competitively.
Optimising your web performance with EdgeSpeed also ensures Google can discover and update your content efficiently.
How EdgeSpeed enhances SEO though Web Performance
EdgeSpeed is designed to deliver immediate and ongoing web performance improvements — with no need for a full site overhaul. In the context of the March 2025 Core Update, here’s how it directly strengthens your SEO performance:
Improves Largest Contentful Paint (LCP): Accelerates the loading of key content using techniques like preloading, compression, critical CSS, and more.
Optimises Interaction to Next Paint (INP): Enhances interactivity via smart JavaScript management with SmartJS and SmartINP.
Stabilises Cumulative Layout Shift (CLS): Prevents irritating layout shifts through automatic image dimension handling and smart visual rendering.
Reduces Time to First Byte (TTFB): Improves perceived speed and optimises crawl budget through advanced caching strategies.
Bottom line: A smoother, faster user experience that maximises your SEO potential in an environment where user expectations are higher than ever.
Case study: How Rakuten boosted SEO Visibility and crawl efficiency with Fasterize
Rakuten, a leading player in e-commerce, faced critical challenges in web performance:
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Delivering fast pages to improve user experience
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Optimising Core Web Vitals for better SEO rankings
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Increasing the number of pages crawled and indexed by Google
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Freeing up technical teams through automated Webperf
After deploying Fasterize’s SaaS solution, the results were clear within a few months:
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+25% SEO traffic increase, based on Sistrix data
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Up to +500% more new pages discovered by Google
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Massive load time reduction, with TTFB down 66% on mobile and 49% on desktop
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Improved CLS, resulting in stronger visual stability
Thanks to continuous optimisation without code changes, Rakuten significantly strengthened UX, crawl efficiency, and SEO visibility — proof that Web Performance, SEO, and Crawl Budget are now inseparable pillars of search success post-Core Update.
Conclusion: Web Performance as a strategic SEO investment
The March 2025 Core Update confirms a fundamental shift: perceived quality by the user now outweighs traditional keyword-driven optimisation.
Improving web performance is no longer just a technical concern — it’s a strategic investment to protect and grow your SEO.
With EdgeSpeed, Fasterize helps you meet this challenge, delivering a fast, seamless, and satisfying user experience — essential for succeeding in the SEO landscape of 2025 and beyond.
Let’s be clear: while UX is now an essential — and unavoidable — part of SEO, it doesn’t replace the foundation — delivering content that is relevant, trustworthy, and genuinely valuable to your audience.
