Is the correct question worth it? When an ecommerce in PrestaShop has a TTFB time of less than 200ms, it falls within the Web Vitals metrics and loads in less than 1.4s or less. In the images in the example we used a clean installation of PrestaShop 1.7.7.8 whose full loading is less than 800ms and despite this the score is just over 80.
It is a score not a performance index
Can we go further? Yes, with small changes we can reach 90, with a customization of the template and database optimization we can also reach 100, but the investment in hours of work and the sacrifices to be made (no Page Builder, no external JS) make the solution practically too much. expensive to the source of practically no, or almost no, real improvement.
Like a racing car, pure performance is achieved by reducing its weight as much as possible.
It is enough just to carry out the same test on large ecommerce for example Amazon.com to notice that not even they invest to reach high scores in this metric, even if 0.1 ms of loading time less for them means hundreds of thousands of euros in more turnover. . In fact, they invest time in Web Vitals metrics and load times by balancing needs with performance.