sourcebioscience.com website review

17 files block the first paint until they finish downloading. Deferring or inlining them could save about 2.4 s.

About 262 KiB of JavaScript is downloaded but never used on this page. Google estimates it would make the page about 1.1 s faster on a phone.

Your mobile performance score is 65 (desktop: 93). Pages that score under 90 lose visitors before the first paint.

6 files are served with short cache lifetimes, so returning visitors download them again (131 KiB).

Google Tag Manager costs a phone 215 ms of main-thread work and 333 KiB of downloads while your page loads. Loading it after the page is usable, or only on the pages that need it, takes that off the critical path.

6 third-party services load with your homepage (Google Tag Manager, Hubspot and hsappstatic.net and others), adding 615 KiB and 343 ms of main-thread time.

2 long tasks block the main thread while loading, the longest for 134 ms. During a long task the page ignores taps.

About 85 KiB of CSS is downloaded but never applied on this page.

Web fonts hide text while they load. Setting font-display: swap shows text immediately (about 50 ms).

Polyfills for old browsers add 28 KiB JavaScript that modern phones do not need.

18 KiB could be saved by minifying JavaScript.

Desktop scores 93 but mobile only 65. A gap that wide usually means heavy scripts and images that hit phones hardest.

Critical files load one after another instead of in parallel (3 chains). Preconnecting to key origins and preloading the hero image shortens the chain.

Scripts make the browser recalculate the layout repeatedly while the page loads, which wastes processor time on phones.

Real Chrome users on phones do not pass Google's Core Web Vitals on this page (28-day field data from the Chrome UX Report (opens in a new tab)). Google uses this in ranking.

Your largest element takes 11.4 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the element shown below.

The page becomes fully interactive after 11.6 s. Good is under 3.8 s.

The first text or image appears after 3.2 s on a phone. Good is under 1.8 s.

Real visitors wait 820 ms for your server to start answering (75th percentile). Good is under 800 ms.

Visually, the page fills in at 5.2 s (Speed Index). Good is under 3.4 s.

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' tap response (inp) went from 112 ms to 119 ms at the 75th percentile (Chrome UX Report (opens in a new tab) history).

1 image (52 KiB) is JPEG, PNG or GIF. The same pictures as WebP or AVIF are usually much smaller at the same quality, and every current browser shows them.

By the Sustainable Web Design model, a visit to your homepage emits about 0.42 g of CO₂e: 50.3 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

Elements must only use permitted ARIA attributes: 9 elements on the page fail this check, rated serious by axe-core.

1 text element doesn't have enough contrast against the background to read easily, especially outdoors on a phone.

Landmarks should have a unique role or role/label/title (i.e. accessible name) combination: 1 element on the page fails this check, rated moderate by axe-core.

All page content should be contained by landmarks: 1 element on the page fails this check, rated moderate by axe-core.

ARIA role should be appropriate for the element: 2 elements on the page fail this check, rated minor by axe-core.

Headings skip levels (h1 → h3), which makes the page harder to scan with a screen reader.

4 links have no real href, so search engines can't follow them.

The homepage links to 148 pages on sourcebioscience.com and 7 external pages.

There is no https://sourcebioscience.com/llms.txt, a short Markdown guide to your key pages for AI tools (llmstxt.org). It is optional and few AI tools read it yet, so treat it as a cheap extra.

We fetched 15 pages linked from your homepage (of 72 found) and read each the way a search engine does.

12 of 28 tappable elements near the top of the page are smaller than 24 px, hard to hit with a thumb.

1 third-party cookie is set on load; browsers are restricting these, so whatever relies on them breaks.

2 images are displayed at the wrong aspect ratio, so they look stretched or squashed.

Chrome logged issues while loading the page (“Cookie”).

No phone number or email link on the homepage, so ready-to-buy visitors have one fewer way to reach you.

No guarantee or risk reducer (money-back, free trial, no credit card) is mentioned, which is often what tips a hesitant visitor.

The homepage carries about 974 words of visible text.

Before a visitor clicks anything, the page loads Google Analytics, Google Tag Manager and HubSpot (measured from a US location before any click). No consent tool was detected. Visitors from the EU, UK and several US states must be asked first.

Opening the homepage sets 6 cookies (measured from a US location before any click).

No known cookie consent tool loads with the page. Some sites build their own banner, and some only show one to visitors from the EU.

Loading the homepage contacts 18 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.