Website speed is not a technical detail—it’s a critical business factor that affects conversion, retention, Google visibility, and user trust. In their Open Tech 2025 talk, Alejo Fonseca and Juan Londoño walked through a step-by-step approach to improving web performance using Core Web Vitals, CDN and edge strategies, server-side rendering, image CDNs, and frontend best practices. Through a real case using Spartacus, they demonstrated how they improved performance from 40% to over 90%—without backend access—and reflected on the strategic role of speed in today’s digital ecosystem.
In the physical world, if a store door doesn’t open, you try again.Online, that never happens.
If a page doesn’t load within a couple of seconds, users close the tab and move on.
No anger, no complaint—just competitors two clicks away.
That was the idea Alejo Fonseca and Juan Londoño used to open their talk at Open Tech 2025:
“Web performance isn’t a technical issue—it’s a business issue.”
Every second (or fraction of a second) translates into lost users, abandoned carts, mistrust, and revenue loss.
As they put it—with surgical clarity:
“A slow store loses sales, retains fewer customers, and slows its own growth. It doesn’t matter how good your product is. If your page doesn’t load, your business doesn’t work.”
Users no longer compare your site to competitors in your industry.
They compare it to Instagram, TikTok, and YouTube.
Apps that load in milliseconds, never freeze, never hesitate.
That’s the mental benchmark.
No one thinks:“Well, this ecommerce must be slower because it sells mattresses.”
If the page lags, the user abandons and finds another option.
As highlighted in the talk:
A 1-second delay can drastically reduce conversion.
Large companies lose millions to slow performance.
Small businesses can stagnate from not optimizing.
In simple terms:
Speed is no longer a nice-to-have; it’s an essential part of the product.
Google observed user behavior and turned it into concrete metrics: Core Web Vitals—the holy trinity of web performance.
Alejo and JP explained them in simple, human terms:
How long it takes for the main content to appear.If nothing shows up, the user feels like nothing is happening.
How much the layout “jumps” during loading.That annoying moment when the button moves just as you try to click it.
How fast the page responds to user interaction.If the user clicks and nothing happens, it’s game over.
These metrics not only measure quality—they directly impact SEO.
Google simply shows slow pages less.
As the speakers said:
“No matter how much marketing you put behind a site, if it’s slow, it won’t be seen.”
A fast page:
communicates professionalism
builds trust
encourages word-of-mouth
increases sales
reduces abandonment
And the impact is measurable.
Amazon found that 100 ms can equal 1% fewer sales.
Google reported that 0.5 seconds faster can increase traffic by 20%.
Few technical factors have such a direct impact on profitability.
The speakers highlighted two key tools:
Lighthouse
WebPageTest
They audit and identify performance issues like unnecessary JavaScript, heavy images, server issues, lack of caching. And Lighthouse is precisely where the practical case began.
For the demo, they used Spartacus—well-known to the Pyxis team.
The initial Lighthouse audit showed:
Performance: 43%
Accessibility: good
Best practices: acceptable
SEO: low
All this using only the public backend—no internal optimizations allowed.
The goal: push performance above 90%.
Did they make it?Yes.Was it easy?Not at all.
Before applying advanced techniques, the foundation needed strengthening:
Load only what the user needs, when they need it.
Shrink JavaScript size:fewer heavy libraries, dead code elimination, more efficiency.
Avoid layout shifts by defining width and height for images and containers.This significantly improves CLS.
Good practices, subscription control, modern HTML, removing unnecessary dependencies.
This “carpentry work,” as Alejo and JP called it, is what allows more advanced improvements later.
A page doesn’t rely only on its code.Infrastructure plays a huge role.
1. CDN (Content Delivery Network)
A global distributed network that sends content from the server closest to the user.
Concrete benefits:
lower latency
better availability
faster pages
reduced load on the main server
built-in failover
If you have users in multiple countries, a CDN is mandatory.
2. Edge Computing
The “middle layer” between server and user.
It allows:
smart caching
immediate responses without hitting the backend
fine-grained rules: what caches, for how long, what bypasses
This alone improved performance by about 20 points.
3. Vercel / Firebase Hosting + Client-Side Rendering
Deploying the frontend on performance-optimized networks adds several speed points.
This stage took Spartacus from 43% to roughly 80–85%.
Still not enough.
4. Server-Side Rendering (SSR)
This was the game changer.
Rendering the page on the server and sending it pre-built dramatically speeds up perceived load.
Benefits:
content visible much faster
better SEO
better performance on low-power devices
SSR makes performance hardware-independent.
5. Image CDN (Cloudimage)
The star of the show.
A specialized image CDN:
compresses automatically
switches formats
resizes
serves optimal images per device
caches intelligently
As they put it:
“An ecommerce is basically a page full of images. Optimizing them means optimizing everything.”
This is what finally pushed performance past 90%.
Final scores:
Performance: 93%
Accessibility: 100%
Best practices: excellent
SEO: 92%
It could have been even higher with backend control.
The goal wasn’t 100%.
The last 6–7% comes with disproportionate cost and minimal real benefit.Even Apple sits around 89%.
Perfection rarely pays off.
Key takeaways from the Q&A:
Can you cache “everything”?
No.The cart, for example, must remain dynamic.
Can a slow backend ruin everything?
Yes.That was the main ceiling in this case.
Chrome vs. Safari vs. Firefox?
Differences exist, but Lighthouse and PageSpeed provide balanced measurement.
Is 99% possible?
Yes—but it’s not worth it for most businesses.The complexity outweighs the marginal gain.
Optimizing performance is not “making the page load faster.”
It is a business strategy affecting:
sales
branding
user perception
retention
SEO
trust
overall experience
As Alejo and JP put it:
“Performance is part of the product. It’s what makes the user stay and buy.”
And:
“Google updates its metrics all the time. You have to stay alert.”
Performance is not a one-time job—it’s a continuous practice.
The talk made one thing clear:Web speed is not a trend.
It will keep growing because:
standards get tougher
technologies allow deeper optimization
Google continually evolves metrics
users expect instant results
Pyxis positions itself as a space that:
blends engineering and business strategy
monitors the market
experiments with new tools
embeds performance from day zero
helps clients build fast, competitive digital platforms
Web performance is not just about speed:
It’s about vision, strategy, and design.
And Pyxis is committed to giving every client—big or small—the speed their business needs.
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