Google Tag Manager  module allows you to integrate Google Tag Manager on your PrestaShop site so that you can track and gather valuable visitor data from your website and make...

Best customer rating and review module for Prestshop, and increase your conversion rate significantly! ,  Easily add the badge and orders confirmation module on your shop

Google Language Translator is the best PrestaShop Translation module available for translating your website into over 105  different languages. simple install and working

Fast and optimized pages lead to higher visitor engagement, retention, and conversions. Increase page load speed.
The Page Speed Module help you to get a passing grade in Google Page Speed Insight.

GZIP compression is bundling (zipping) pages on a web server before the page is sent to the visitor.This saves bandwidth and therefore increases the loading speed of the page significantly.

PrestaShop Static HTML Block module allows you to create custom HTML blocks to display special information such as text, widgets, custom CSS/HTML or other stuff. You can add special blocks in footer, header, CMS pages or any other page in the left/right columns, with the ability to add CSS effects.Improve SEO and site information

Intercom.io customer communication platform with a suite of integrated products for every team – including sales, marketing, product, and support.

Klarna Checkout is a complete online checkout solution designed to increase sales and customer loyalty, including Pay now, Pay later, and Financing options.

Demo : https://graceofsweden.se/module/klarnaofficial/checkoutklarnakco
in addon very high price see here : https://addons.prestashop.com/en/express-checkout-process/90132-klarna-checkout.html

Lazy Loading will increase website speed by loading all the images after your website load completely on customer's end.
Show Animated GIF Image during the loading of your website with each product. You can set time interval to delay in loading images

Page load times can be significantly improved by asking visitors to save and reuse the files included in your website

 Mass product Friendly URLs regenerate Regenerate missing products & images links - by shop and language - PrestaShop . This module a few languages added to your shop and since Product Friendly URL generate by shop and language, now I would like to generate SEO. missing product images url and product url generate , Missing products link generate  automatically. 

Minify HTML CSS JS is a very small and efficient extension. It will minify HTML including inline CSS and JS code.