Optimization of Core Web Vitals (OpenCart) for Google PageSpeed — Mobile and PC versions
Order description:
We are looking for an experienced frontend developer/OpenCart specialist to optimize the loading speed of the website (categories and product cards) according to Google Core Web Vitals requirements.
About the project:
* CMS: OpenCart.
* Specifics: The site operates in catalog mode (no cart or checkout).
* Volume: 2900 items.
* Server part: Already optimized (runs on OpenLiteSpeed).
* Stack: Work is done exclusively with the template code, modifiers, and frontend. No work with the database.
What needs to be done (Technical task):
1. Delayed loading of scripts (Delay JS):
* Problem: Third-party analytics scripts (GTM, Google Tag) block the main thread on mobile devices for about 4.3 seconds.
* Task: Set up delayed execution of these scripts. The scripts should activate strictly on the first user action (first scroll, tap on the screen, or mouse movement).
* Important: Data collection, analytics, and ad functionality must remain intact.
2. Fixing the CLS metric (Layout Stability):
* Problem: The page "jumps" and shifts during image loading.
* Task: In the style files or theme template, hardcode the HTML attributes width and height for all product images in the catalog (listings) and product cards.
* Goal: Reserve space for images in the DOM tree until they are actually loaded to prevent content shifting. Ensure that responsiveness (CSS) is not broken.
3. Optimization of the critical path (LCP):
* Task: Add the fetchpriority="high" tag for the main product image on the first screen. This will instruct the browser to load the main product photo as a priority.
Requirements for the performer and acceptance conditions:
1. No unnecessary modules: Work is performed with clean code/modifiers, without installing additional third-party or paid optimization plugins.
2. Security and layout: You are fully responsible for the layout. After making changes, the visual display of the site on mobile and PC, as well as functionality (filters, photo switching in the gallery, menu) must remain unchanged.
3. Criteria for job submission (DoD): Provide a screenshot and a link to a live test report from Google PageSpeed Insights (for the mobile version). The performance score must be no lower than 75 points, and the CLS metric must be no more than 0.1 (in the green zone).
Changes must be made strictly through modifiers (OCMOD) or a copy of the theme to avoid overwriting core updates.
In your response, please indicate:
1. Have you had experience configuring Delay JS specifically for GTM on OpenCart?
2. The estimated time for task completion.
3. The cost of the work.
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4 days89 USD
140 4 days89 USD
Good day.
I am responding to your three questions:
1. Experience with Delay JS for GTM — yes. Approach: a JS wrapper that blocks the initialization of GTM until the first user action (scroll/click/mousemove). After it triggers — standard launch, analytics, and advertising are fully preserved.
2. Timeline — 3–4 days.
3. Cost — 4000 UAH.
Regarding the other tasks: I will address CLS through width/height in the listing and product card templates, and I will check that max-width: 100% in CSS does not break responsiveness. I will set fetchpriority="high" on the main product image. All changes will be made via OCMOD or a copy of the theme; I will not touch the core.
One clarification regarding the delivery criteria: I guarantee three specific points of the technical specification — Delay JS, CLS, and LCP. The overall PageSpeed score depends on the state of the entire site, so it would be worth reviewing the current report together before starting — to understand whether these changes alone will be sufficient for ≥75, or if there is anything else that might pull it down.
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3 days56 USD
232 3 days56 USD
Good day! I did exactly this kind of optimization for OpenCart — Delay JS through the first action listener (scroll/touch/mousemove), so that GTM and Google Tag load on event and all statistics remain intact, plus width/height on catalog images against CLS and fetchpriority=high on the main photo of the card under LCP. Everything with clean modifiers, without third-party plugins. Just let me know, is it the standard Journal theme or a custom template — this will determine where to intercept the output of images in the listing. I will complete it in 2-3 days and provide screenshots of PageSpeed before/after for mobile.
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3 days89 USD
344 1 0 3 days89 USD
Hello! I have practical experience specifically with this set of tasks on OpenCart — Delay JS via GTM, CLS, and LCP — all through OCMOD / theme copy, without paid optimization plugins.
Regarding your questions:
1. Yes, I have configured Delay JS for GTM on OpenCart. I launch scripts strictly on the first user action (scroll / tap / mouse movement), but I also set an additional safety timeout — to meet both of your requirements: to delay the launch and not lose any sessions. A pure interaction-only delay subtly "eats" bounce traffic (those who entered and left without interaction do not get into GTM), and the timeout addresses this. Thus, the collection of statistics and the performance of advertising are preserved in full.
2. Timeline: 2–3 working days with testing on mobile and PC.
3. Cost: 4000 UAH.
I will address CLS through width / height + aspect-ratio in styles — space for the photo is reserved, but responsiveness is not broken.
… I am ready to take this on. Please send the link to the website — I will take a look and confirm the timeline.
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3 days67 USD
871 10 0 3 days67 USD
I will perform optimization according to the technical specifications (Delay JS, fixing CLS, fetchpriority, through OCMOD without third-party modules). After making changes, I will conduct testing in Google PageSpeed Insights and, if possible, achieve the target metrics. If there are limitations related to other elements of the site that are not included in the technical specifications, I will inform you about them separately.
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2 days78 USD
96760 1276 1 10 2 days78 USD
Hello. I have extensive experience in speeding up websites. I am ready to collaborate.
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7 days267 USD
1510 10 0 7 days267 USD
Good day! We have experience in optimizing OpenCart to meet Google Core Web Vitals requirements. We achieve this through caching settings, image optimization, resource minification, and eliminating blocking scripts. This will ensure high PageSpeed scores for both mobile and desktop versions, improving rankings and user experience. We are ready to start analyzing and implementing technical solutions.
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Вітаю, покажіть сайт, щоб розуміти масштаби проблеми
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ТЗ написано AI (з помилками), виконавці ставлять ставки з AI текстом (не думаючи над реальною роботою). По факту AI проти AI )))
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