Landing page speed is a media buying problem
You are paying for the visitors who leave before the page appears.
2 min read
Key takeaways
- Measure on a mid-range phone on a real network, not on your laptop.
- Largest Contentful Paint is the number most closely tied to paid conversion rate.
- Hero images and third-party scripts cause most of the damage.
- A one-second improvement is usually less expensive than a CPM reduction of the same value.
On this page5 sections
Media buyers spend hours optimizing bids and minutes thinking about the page that receives the traffic. The arithmetic argues for the opposite ratio: the page is the only part of the funnel where you can improve results without paying anyone.
Measure the way your traffic arrives
Your landing page is fast on the office connection. Your traffic arrives on a mid-range phone on a mobile network. Test on that: a throttled connection, a mid-tier device, a cold cache. The gap between the two measurements is often two to four seconds.
What usually causes it
Cause
Unoptimized hero image
- Typical cost
- 1–3 s
- Fix
- Modern format, correct dimensions, preload
Cause
Third-party scripts in the head
- Typical cost
- 0.5–2 s
- Fix
- Defer them, or remove the ones nobody reads
Cause
Web fonts blocking render
- Typical cost
- 0.3–1 s
- Fix
- Subset, preload, use a fallback that matches
Cause
Redirect chains from the ad
- Typical cost
- 0.2–1 s
- Fix
- Link straight to the final URL
| Cause | Typical cost | Fix |
|---|---|---|
| Unoptimized hero image | 1–3 s | Modern format, correct dimensions, preload |
| Third-party scripts in the head | 0.5–2 s | Defer them, or remove the ones nobody reads |
| Web fonts blocking render | 0.3–1 s | Subset, preload, use a fallback that matches |
| Redirect chains from the ad | 0.2–1 s | Link straight to the final URL |
The redirect nobody audits
Ad platforms follow the link you give them. If that link redirects twice before the page renders, you have added latency for every single visitor, and you are paying for all of them. Check the destination URL in the ad against where the browser actually lands. Redirects through unrelated domains can also cause a destination to fail review.
Measure it the same way every time
Pick one tool and one setup, and use them for every measurement, so this week's number can be compared with last month's. Google's PageSpeed Insights shows field data from real Chrome users when a page has enough traffic, next to a lab test; the field data is closer to what your paid visitors actually experience.
- Track the three Core Web Vitals: Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift.
- Measure the exact URL the ad links to, with its tracking parameters, not the bare homepage.
- Log each result with the date and the change you made, so you can connect it to conversion rate later.
A short audit you can run today
- 1Open the live ad, tap the link on a phone, and time it.
- 2Check for redirects between the ad URL and the final page.
- 3Find the largest element on the page and measure when it appears.
- 4List third-party scripts, then defer or delete everything that is not needed to render.
- 5Measure again, then compare conversion rate over the following week.
The least expensive media you will ever buy is the page you already paid to send people to.
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Written by
Krög editorial team
Account managers, compliance and billing
Written by the people at Krög who open, fund and support advertising accounts for verified businesses every day. Platform rules change often. If something here is out of date, tell us on Telegram.
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