Website Speed and Conversion: What the Data Says

Let me tell you a story.

A SaaS company was losing. They had good product, solid copy, clear value prop. But they were converting at 2%. Competitors with better designs were converting at 5%.

They hired a copywriter. Conversion stayed at 2%.

They hired a designer. Conversion stayed at 2%.

They ran A/B tests on hero copy. Conversion stayed at 2%.

Then they checked their page speed. Their home page was loading in 4.2 seconds. By the time the page finished loading, 60% of visitors had already bounced.

They optimized for speed. Down to 1.8 seconds. Conversion jumped to 5%.

Same copy. Same design. Same offer. Just faster. 150% increase in revenue.

They weren't a copywriting problem. They weren't a design problem. They were a speed problem.

This is more common than you'd think. Let's talk about the data.

The Speed-Conversion Relationship

Google's research is clear:

• 0-1 second load: 80% of users stay. Optimal conversion conditions.
• 1-3 seconds: 40% of users bounce per second of additional delay.
• 3+ seconds: 53% of mobile users bounce. You've lost the majority.

Let's run the numbers on a hypothetical site:

Speed	Users Stay	Converted (2% baseline)	Revenue Impact
0.8 seconds	95/100	1.9 conversions	Baseline
2.0 seconds	60/100	1.2 conversions	-37%
3.5 seconds	40/100	0.8 conversions	-58%
5.0 seconds	25/100	0.5 conversions	-75%

A 5-second site is losing 75% of its potential revenue compared to a fast site. And this assumes the same conversion rate for those who do stay—which isn't true. Slow sites also convert slower visitors at lower rates.

The Mobile Impact Is Worse

On mobile, the problem is even more acute.

Mobile users have lower patience. They're on spotty 4G. They bounce faster.

• 1-3 seconds on desktop: OK, user might wait
• 1-3 seconds on mobile: UNACCEPTABLE. User bounces.

70% of your traffic is mobile. If your site is optimized for desktop and slow on mobile, you're losing 70% of your customers.

What Actually Matters: Core Web Vitals

Google doesn't just measure "page load time" anymore. They measure three specific metrics called Core Web Vitals:

1. LCP (Largest Contentful Paint) — How fast does the main content appear?

• Good: <2.5 seconds
• Poor: >4 seconds

If your hero image takes 4 seconds to load, users think the page is broken.

2. FID (First Input Delay) — How responsive is the page to clicks?

• Good: <100ms
• Poor: >300ms

If a button takes 500ms to respond when clicked, users think it didn't register. They click again. Confusion.

3. CLS (Cumulative Layout Shift) — Does the page jump around?

• Good: <0.1
• Poor: >0.25

If ads load and push the page down, and the user was about to click the signup button but now they click an ad instead—that's CLS failure. Users hate it.

How to Actually Fix Your Site Speed

If your site is slow, here's the diagnosis framework:

1. Measure first. Use Google PageSpeed Insights or GTmetrix. Get the actual numbers.

2. Find the culprit. Usually it's one of three things:

• Unoptimized images (50% of sites)
• Too much JavaScript (30% of sites)
• Slow hosting (20% of sites)

3. Fix it.

• Compress images to <100kb per image
• Lazy-load non-critical JavaScript
• Upgrade to managed hosting (not shared hosting)
• Use a CDN to serve assets globally
• Enable GZIP compression on the server

A good engineer can usually cut load time in half with these fixes. No redesign. No new code. Just optimization.

The Real Cost of Slow Sites

Let's be concrete. You're a SaaS company. £100/month per customer. 1,000 visitors/month. 2% conversion rate.

Fast site (1.5 seconds):

• 1,000 visitors → 950 stay → 19 convert → £1,900/month

Slow site (4 seconds):

• 1,000 visitors → 400 stay → 8 convert → £800/month

Difference: £1,100/month. £13,200/year.

To lose that much revenue by ignoring speed is like leaving money on the table. Actually, worse—you're actively driving it away.

Speed Is Non-Negotiable

I want to be crystal clear: speed is not a "nice to have" feature. It's not a "good to optimize for later." It's foundational.

You can have the best copy in the world. If your site takes 5 seconds to load, you won't sell anything.

You can have stunning design. If images take forever to appear, the beauty is wasted.

Speed is table stakes for professional websites. If your site is slow, everything else is irrelevant.

At Forge, every website loads in under 1 second. Not because we're magic. Because speed was a first-class concern from architecture to deployment. It's built in, not bolted on.