LCP metrics: why they matter and how Mailocator approaches them

Web performance has become a key factor not only for user comfort but also for SEO. One of the most important metrics in this area is LCP – Largest Contentful Paint. This metric affects how quickly visitors see the main content of a page and has a direct impact on how Google and other search engines rate your website.

In this article, we will explain what LCP actually measures, why it is essential for indexing, and how Mailocator is the only tool on the market that handles campaign display in a way that does not harm LCP.

What is LCP (Largest Contentful Paint) and why is it important?

LCP is one of the Core Web Vitals metrics. It measures the time it takes for the most important (largest) visible element on the page to render for the user, typically:

• the main image in the hero section,
• a large headline,
• a background image,
• or a block with introductory text.

What does LCP evaluate?

• How quickly the user gets the first meaningful content.
• To what extent the page is visually ready for interaction.
• Whether the user has to wait unnecessarily long for the content that primarily interests them on the page.

Impact on SEO and indexing

Poor LCP (above 2.5 seconds) can mean:

• a lower score in Core Web Vitals,
• a drop in search results,
• a higher bounce rate,
• a negative signal for crawling and indexing prioritization.

Google considers LCP to be an important signal of page quality. Pages with slow LCP may be indexed less readily or later, especially when it comes to content-rich e-shops.

Where to measure LCP: tools and plugins

There are several ways to easily verify LCP metrics. The basic option is Chrome DevTools, where you simply start recording page loading in the Performance panel and then all important milestones, including the LCP value, are displayed in the overview. Another quick external test is Google's PageSpeed Insights – after entering the URL, it displays both laboratory measurements and real-world traffic data (CrUX) along with recommendations for optimization.

For daily checks, the most convenient option is the Web Vitals plugin for Chrome, which shows LCP, FID/INP, and CLS in real time during normal web browsing, so developers can immediately see whether a given page meets Core Web Vitals standards.

Core Web Vitals are three key metrics from Google that measure the actual user experience on a website – loading speed (LCP), interactivity (INP), and visual stability (CLS). They help identify technical issues that slow down pages and have a direct impact on SEO and overall user satisfaction.

How campaigns affect LCP and where the problem arises

Many webmasters and operators of e-shops or content platforms still do not pay enough attention to the LCP metric, even though pop-up campaigns can significantly affect it, especially if:

• they are inserted into the page immediately after loading,
• the campaign engine loads templates, styles, or images before loading the content,
• there is an intentional delay in display (e.g., 5-10 seconds), but the tool still blocks the structure from rendering.

A typical problem with common pop-up tools:

Content-intensive campaigns launch immediately after the page loads, unnecessarily prolonging the rendering time. Similarly, deferred campaign loading that does not wait for user interaction can still negatively affect the LCP metric – even if the pop-up itself appears later. We often see this with Wheel of Fortune-type games and similar instant solutions, which are not usually very optimized technically and load immediately regardless of the impact on website performance.

This results in:

• unnecessary load on the rendering pipeline,
• prolonged LCP,
• interference with Core Web Vitals.

Google detects these processes as a load on the main thread, which should be dedicated to rendering important elements.

Solution in Mailocator: a technologically advanced approach to LCP and campaign loading

As a specialized display platform, Mailocator has long been deeply involved in LCP issues. When designing campaigns and their triggers, loading times are actively monitored and optimized, including the use of our own cache, to minimize the load on the rendering process. Another key principle is working with user interaction: the campaign does not start immediately after the page is loaded, but only when the user shows minimal activity, which significantly reduces the risk of negatively affecting LCP metrics.

This technologically advanced approach is rather an exception in the industry. The vast majority of common tools and plugins load campaigns immediately or regardless of interaction, which can slow down rendering and ultimately damage the performance of the page and its indexing in search engines.

A website that loses its position in organic search due to an inappropriate solution often has to compensate for the drop in traffic with higher spending on paid marketing.

Mailocator, on the other hand, emphasizes technical precision and minimizing the impact of campaigns on website performance, which is essential for maintaining good results in Core Web Vitals and organic search.

Why Mailocator's solution is technologically exceptional

It is optimized for Core Web Vitals from the ground up

It does not add unnecessary requests at critical moments

It allows you to delay campaign initialization beyond the LCP threshold

It eliminates the risk of pop-ups affecting ranking or crawling

Applies to all types of campaigns – subscribe, inventory, banners, CTA, gamification