The verdict in three sentences
A 450 ms mobile INP on a B2B trade catalogue means every tap on an appellation or vintage filter feels stuck, and buyers who order between lunch and dinner service end up phoning their account manager or ordering elsewhere. On the UK market, an audit costs £1,000 to £3,000 and the fix £3,500 to £10,000, aiming for Google's 200 ms threshold. The gain we see on this kind of catalogue, 8 to 15% more mobile orders, usually pays the work back within a quarter.
Why INP hurts a wine merchant's catalogue
Since March 2024, Interaction to Next Paint has replaced First Input Delay among the Core Web Vitals. Where the old metric only measured the first tap, INP keeps one of the slowest interactions of the whole visit. A trade catalogue is made of repeated interactions: tick "Pessac-Léognan", untick "2019", sort by price, add a case of 12, change the quantity.
On the catalogues we audit, the causes are almost always the same:
- filtering runs entirely in the browser and recalculates the full list of 2,000 to 3,000 lines on every tap;
- the page ships more than 800 KB of compressed JavaScript, much of it for features never used on mobile;
- third-party scripts (live chat, tag manager, session recording) hold the main thread at the moment of the tap;
- the side basket rebuilds itself entirely on each quantity change.
Google sorts INP into three bands. A catalogue at 450 ms sits in "needs improvement", 50 ms away from "poor".
| INP band | Threshold | How it feels to a buyer on a phone |
|---|---|---|
| Good | 200 ms or less | Filters respond instantly |
| Needs improvement | 200 to 500 ms | Visible hesitation, frequent double taps |
| Poor | Over 500 ms | Page feels frozen, abandonment |
| Merchant's current state | 450 ms (75th percentile, mobile) | Drop-off on combined filters |
| Realistic target after the fix | 150 to 190 ms | Smooth browsing on 4G |
The fixes that actually bring INP down
Step one is measuring in the field, not in the lab. CrUX data in Search Console shows the trend, but you need to instrument the site with the web-vitals library in attribution mode to learn which interaction, on which element, causes the spikes. Two weeks of data are enough with 1,800 active trade accounts.
| Fix | Typical INP gain | Estimated effort | 2026 order of magnitude |
|---|---|---|---|
| Server-side filtering with a URL per filter | 150 to 250 ms | 5 to 8 days | £2,000 to £4,500 |
| Virtualised product list | 60 to 120 ms | 2 to 3 days | £800 to £1,800 |
| Breaking up long tasks and yielding to the main thread | 40 to 100 ms | 2 to 4 days | £800 to £2,200 |
| Deferring third-party scripts until after interaction | 30 to 80 ms | 1 to 2 days | £400 to £1,000 |
| Partial basket updates | 20 to 60 ms | 1 to 2 days | £400 to £1,000 |
| Shipping less JavaScript to mobile | 30 to 70 ms | 3 to 5 days | £1,200 to £2,600 |
Gains do not simply add up, but server-side filtering alone solves half the problem. It also has a valuable side effect: each useful combination ("Saint-Émilion grand cru 2020") gets an indexable URL, which strengthens the catalogue's SEO too.
At Kolonell, this kind of work falls under web application development and is quoted after the audit, because everything depends on the platform (Magento, Shopify Plus, custom build). Ongoing monitoring can then sit in a monthly SEO plan at 100,000, 200,000 or 350,000 FCFA a month.
What an INP under 200 ms is worth
A B2B catalogue does not live on visits but on repeat orders. The right calculation therefore starts from mobile order volume, not traffic.
| Indicator | Before the fix | After the fix |
|---|---|---|
| Mobile INP (75th percentile) | 450 ms | 180 ms |
| Share of orders placed on mobile | 30% | 32 to 34% |
| Abandonment after using a filter | 38% | 25 to 29% |
| Mobile orders per year | 3,240 | 3,500 to 3,725 |
| Calls to the sales desk for simple orders | 120 a month | 80 to 95 a month |
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Mini case study
Helen, sales director of a London wine merchant, manages 1,800 trade accounts placing an average of 6 orders a year at £560, so 10,800 orders. 30% come through mobile: 3,240 orders.
Budget: a £2,200 audit and a £7,000 fix, so £9,200. With a cautious 8% rise in mobile orders, the merchant gains 259 orders a year, or 259 x £560 = £145,040 in revenue. At a 20% gross margin, that is £29,008 a year, or £2,417 a month. The work pays back in 9,200 / 2,417 = 3.8 months. At the top of the range (15%), payback drops under two months.
FAQ
Does INP really affect Google rankings?
It is one signal among many, with modest weight compared with content relevance. Most of the gain comes from conversion: going from 450 to 180 ms cuts filter abandonment by about 10 points in our measurements.
How long until Search Console shows the improvement?
CrUX data covers a rolling 28 days. Allow 4 to 6 weeks after release for the report to turn green, whereas the web-vitals library shows the result the next day.
Do we need to change e-commerce platform?
Rarely. In 8 cases out of 10, server-side filtering and trimming scripts are enough to get under 200 ms without a migration, which stays within the £3,500 to £10,000 range.
Are third-party scripts always to blame?
They often weigh 30 to 80 ms at the moment of the tap. You do not necessarily remove them: load them after the first interaction or replace the heaviest ones.
How do we stop INP from degrading again?
Add a performance budget to your release process: any new feature that pushes INP past 200 ms is blocked before it reaches customers. Monthly Core Web Vitals monitoring costs far less than a new audit.
Let's scope your project. An INP audit of your trade catalogue with a prioritised fix plan can be scoped in one call, with the first fixes in production within 3 to 5 weeks. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
