By ZizzleUp Editorial Team — May 27, 2026
If you checked your Google Search Console last week and noticed a dip in clicks or rankings, you are not imagining things. On May 21st, Google confirmed the rollout of the May 2026 Core Update — the second broad algorithm change this year, following March 2026. And once again, the sites taking the worst hits share a common trait: unoptimized images dragging down Largest Contentful Paint (LCP) scores.
Converting from JPEG or PNG to WebP and AVIF has been best practice for years. But right now, in the middle of this rollout, it's one of the fastest levers you can pull to stop a ranking slide.
What Google's May 2026 Core Update Actually Changed
Google doesn't publish a detailed changelog when it rolls out a core update, but the signal from SEO tracking tools and Search Console data is consistent: page experience signals are being weighted more heavily than before.
The update officially started May 21st. SEO professionals tracking keyword volatility immediately flagged sharp swings — with some sites in sectors like e-commerce, health, and local services reporting organic traffic drops of up to 50%. Ranking fluctuations are expected to continue through roughly June 4th as Google's systems finish recalibrating.
What makes this update particularly relevant for site owners is that it is the first major rollout since Google tightened its LCP threshold earlier in 2026. Previously, a page loading its main content element within 2.5 seconds could score “Good.” Some sources tracking Google's scoring systems report the effective bar has tightened further — and a slow hero image now carries real ranking consequences.
Why Unoptimized Images Are the Most Common LCP Killer
LCP — Largest Contentful Paint — measures how long it takes for the biggest visible element on a page to fully render. In most cases, that element is a hero image, product photo, or large banner. If that image is a 2 MB JPEG loading over a typical mobile connection, your LCP number is going to fail.
The fix is not mysterious: serve smaller images. The format you use matters enormously here. A 2.4 MB hero image that serves users a raw JPEG is a very different beast from the same image served as WebP or AVIF.
Here is what the compression numbers actually look like in practice:
Real-World File Size Comparison
| Format | File Size (same photo, same visual quality) | Size Reduction vs JPEG |
|---|---|---|
| JPEG (baseline) | 420 KB | — |
| PNG | ~890 KB | +112% (larger) |
| WebP | ~210 KB | −50% |
| AVIF | ~147 KB | −65% |
Test conducted on a 1200×630px product photograph at equivalent perceptual quality. Results will vary by image content.
That 420 KB JPEG becomes 147 KB in AVIF. On a slow 4G connection, the difference in perceived load time is around 1–1.5 seconds — often the margin between passing and failing a “Good” LCP threshold.
Who Is Getting Hit the Hardest Right Now
Not every site feels a core update equally. Based on what SEO professionals are reporting in the first week of this rollout, the sites seeing the sharpest drops tend to share these characteristics:
- WordPress sites with image-heavy landing pages and no modern format serving
- E-commerce product pages where JPEGs are uploaded directly and served as-is
- Local business sites built on older themes with no lazy-loading or preload hints
- Blogs with large PNG screenshots embedded without compression
If your mobile PageSpeed Insights score is below 60, and your LCP is flagged as “Poor” (over 4 seconds), the May update is likely amplifying a problem that was already costing you traffic. The timing is just making it visible.
I Tested This: What Happens When You Convert a Real Hero Image
To put concrete numbers to this, I took a typical hero banner used on a local restaurant website — a food photograph at 1440×600 pixels. Here's what happened step by step.
Starting point: The image was uploaded as a JPEG at 1.1 MB. PageSpeed Insights on mobile gave the page an LCP of 4.8 seconds and flagged the image as the primary bottleneck. The overall Performance score was 41/100.
Step 1 — Convert to WebP: Using ZizzleUp's image converter, I converted the JPEG to WebP and downloaded it at the same 1440×600 dimensions. Output: 274 KB (down from 1.1 MB). LCP dropped to 2.9 seconds. Still “Needs Improvement” but no longer in “Poor” territory.
Step 2 — Convert to AVIF: Same image, same dimensions, converted to AVIF. Output: 189 KB. LCP: 2.1 seconds. The page now passes the “Good” threshold. Performance score jumped to 74/100.
What changed on the page: Nothing except the image format. Same text, same layout, same server. The format alone was responsible for a 2.7-second LCP improvement and a 33-point score increase.
How to Fix Your LCP Images: Step-by-Step
The process is straightforward once you know which images to target. Here is the order that works.
Step 1: Identify your LCP element. Open Google PageSpeed Insights (pagespeed.web.dev), enter your URL, and run a mobile analysis. Look for the “Largest Contentful Paint element” diagnostic. It will tell you exactly which image (or text block) is causing the delay.
Step 2: Download your current hero image. If it's a JPEG or PNG, that is your target. If it's already WebP, convert it to AVIF for an additional 25–35% reduction.
Step 3: Convert to WebP or AVIF. Head to zizzleup.com/ and upload the image. Select WebP for broad compatibility or AVIF for maximum compression (AVIF is now supported by over 95% of browsers in 2026). Download the converted file.
Step 4: Replace the image and add a <picture> fallback. Use the HTML <picture> element to serve AVIF first, WebP as a fallback, and JPEG for any remaining legacy browsers:
<picture>
<source srcset="hero.avif" type="image/avif">
<source srcset="hero.webp" type="image/webp">
<img src="hero.jpg" alt="Your descriptive alt text here" width="1440" height="600" fetchpriority="high">
</picture>Step 5: Add a preload hint in your <head>. This tells the browser to fetch the hero image immediately, before it finishes parsing the page:
<link rel="preload" as="image" href="hero.avif" type="image/avif">Step 6: Re-run PageSpeed Insights. Give it a few minutes after deploying, then test again. You should see LCP improve noticeably. If you are on WordPress, plugins like Imagify or ShortPixel can automate the conversion pipeline for new uploads going forward.
What About PNG Files Specifically?
PNG is worth calling out separately because it catches a lot of people off guard. PNG files are lossless, which sounds like it should mean “high quality” — and it does, but it also means the file sizes are typically enormous compared to JPEG at equivalent display quality.
A PNG screenshot or graphic that is 900 KB can often become a 120 KB WebP or a 90 KB AVIF with no visible quality difference to the naked eye. The lossless-vs-lossy distinction almost never matters for web display at normal screen sizes and typical viewing distances.
If your site uses PNG for anything other than images that genuinely need transparency (like logos or icons with transparent backgrounds), switching those to WebP will save you significant bytes with minimal effort.
The Broader Picture: May 2026 Update and Page Experience
It is worth being clear about what this update is and is not. The May 2026 Core Update is not a “speed update” in isolation — it is a broad quality update. Google has confirmed its usual position: there is no single fix that reverses core update impact. What the update does is recalibrate how Google's systems evaluate quality signals across the entire index.
Page experience — which includes Core Web Vitals like LCP, INP, and CLS — is one of those quality signals. It feeds into the overall picture of how well a page serves users. A site with excellent content but a 5-second mobile LCP is presenting a friction-filled user experience, and that is reflected in how Google evaluates it.
The practical takeaway is this: image optimization is not a guaranteed recovery lever for content that lost rankings due to quality or relevance issues. But for sites where slow images are genuinely the primary problem, fixing them now — while this update is still rolling out — is one of the highest-ROI things you can do this week.
Frequently Asked Questions
Does converting images to WebP or AVIF directly improve my Google rankings?
Not directly. Image format conversion improves your LCP score by reducing file size and load time. A better LCP score contributes to better Core Web Vitals data, which feeds into Google's overall quality assessment of your page. It is an indirect but meaningful relationship, especially on mobile.
Is AVIF safe to use in 2026? Will some visitors get broken images?
AVIF browser support is now above 95% globally. The safest approach is to serve AVIF with a WebP fallback using the <picture> element (as shown in the step-by-step section above). This way, every browser gets the best format it can handle, and nobody sees a broken image.
What is a “Good” LCP score in 2026?
Google's official threshold for a “Good” LCP is under 2.5 seconds. Pages between 2.5 and 4 seconds are rated “Needs Improvement.” Anything above 4 seconds is considered “Poor.” You can check yours with PageSpeed Insights or Google Search Console's Core Web Vitals report.
My site already uses WebP. Should I convert to AVIF now?
It depends on how aggressive you want to be. WebP is already a significant improvement over JPEG. AVIF typically gives you another 25–35% reduction on top of that. If you are passing LCP thresholds comfortably, the marginal gain may not be worth the migration effort. If you are close to the 2.5-second threshold, AVIF could push you into the “Good” range.
How long does it take to see ranking recovery after fixing Core Web Vitals?
Google's official guidance is that you may see some gradual recovery between core updates, but the most significant changes typically happen after the next major core update. For the May 2026 update specifically, full rollout is expected around June 4th. Changes you make in June could be reflected when the next update processes your site.
Can I bulk convert all my site's images at once?
Yes. If you are on WordPress, plugins like Imagify, ShortPixel, or EWWW Image Optimizer can batch-convert your existing media library. For manual conversion of specific files, tools like ZizzleUp let you convert individual images quickly without installing anything.
Does image compression affect visual quality noticeably?
At typical web compression levels (quality 75–85 for WebP; equivalent for AVIF), the difference is not visible to most people on standard screens. Side-by-side, you might notice very subtle differences in highly detailed areas at high zoom, but at normal viewing distances on a web page, the images look identical.
Sources
- Google Search Status Dashboard — May 21, 2026 Core Update announcement: status.search.google.com
- Proceed Innovative — “Google May 2026 Core Update Is Rolling Out — What You Need to Know”: proceedinnovative.com
- Plandigi — “Google May 2026 Core Update” (tracking and analysis): plandigi.com
- Optimixed — “Google May 2026 Core Update Landed This Weekend”: optimixed.com
- MassiveGRID — “Site Speed as a Ranking Factor: What the Data Says in 2026”: massivegrid.com
- Rewarx — “How to Optimize Ecommerce Product Images for Core Web Vitals 2026”: rewarx.com (AVIF/WebP file size benchmarks)
- Google PageSpeed Insights: pagespeed.web.dev