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Core Web Vitals are great at telling you how a page performs. But they do not always tell you when a specific part of that page became available to users.

It is a common web performance headache: you have optimized your hero images and streamlined your CSS, but your LCP scores are still stuck in the "yellow" zone. Often, the bottleneck isn't the file size- it is the order in which the browser decides to download it.

Single Page Applications have always been a bit of an awkward fit for Core Web Vitals. And not because SPAs are inherently slow.

Web performance improvements often come from small, incremental gains. Better caching, fewer requests, smaller files. Every once in a while though, a new platform feature shows up that makes you pause and think: why has this not been mainstream already?

Speculative loading is one of the few techniques that can fundamentally change how fast a website feels. And a new kid on the block got introduced: prerender_until_script

At RUMvision, our focus is helping site owners make their sites faster. To do that well, we depend on the data browsers give us through APIs. Some of those APIs are already incredibly useful — but not all browsers support them consistently.

For years, site owners have been using Subresource Integrity (SRI) as a way to ensure that third-party scripts can’t be tampered with. However, keeping your script up to date is one of its challenges.

If you’ve been tracking real user performance, you probably already know: Chrome has long supported largest contentful paint (LCP), but Safari until now did not. That’s starting to change, and it’s a big deal if you rely on rumvision for insights.

At RUMvision, we're always looking for smarter ways to optimize web performance data collection. That's why we're excited to announce we've begun rolling out support for a new browser API called fetchLater.

If you're still depending on unload events in your code, you need to act NOW. Chrome is starting to kill these handlers this month, potentially breaking your website's analytics and data-saving features. These events were never reliable on mobile, Safari already ignores them, and soon desktop Chrome will too. Here's why moving to better alternatives won't just save your code—it'll actually improve your site's performance.

Chrome is about to supercharge page navigation for millions of websites by ignoring a common performance-killing HTTP header. This under-the-radar change could dramatically improve your Core Web Vitals with zero developer effort by enabling bfcache for pages with Cache-Control: no-store. How do you know if you will benefit? (Spoiler: if you're using Magento, you probably won't.)

The back/forward cache (bfcache) is the most powerful performance optimization you've never heard of. While teams obsess over milliseconds of server time, they're missing out on entire seconds of improvement that's already built into every major browser.

We're excited to announce the implementation of View Transitions API on our website, enhancing navigation fluidity and user feedback. This helps both us and you as a visitor to smoothly navigate our website from the very start of 2025. This UX update not only makes navigation more visually appealing, it also provides better feedback about page load states.

Almost instant page loading times, with just a small code change, who doesn't want that? Thanks to the Google Chrome dev team, this can be your reality. Want to learn more? Let Barry tell you all about it!

The new LoAF API makes debugging a high INP a lot easier and more insightful, aside from being a new technique it sounds fun. Read and see more about how the LoAF API can help you and how RUMvision makes it insightful for you.

Google Chrome's version 112 brings a significant update to the Largest Contentful Paint (LCP) metric, which will now ignore images with very low content relative to their display sizes. This change aims to improve the accuracy of LCP measurements and help web developers optimize their websites' performance. In this article, we will discuss the changes in LCP and how they may affect a site's metrics.

As of Chrome 106, Chrome will no longer be doing Online Certificate Status Protocol (OCSP) revocation checks by default for Extended Validation (EV) certificates. This led to a direct performance improvement for sites using an EV certification.