The Swift Shopify app guarantees an increase in Core Web Vitals metrics that are a very important ranking factor for Google. Swift even promises to refund you the cost of service if it fails to boost your speed.
When you get connected to one of Swift’s experts, you can be sure that your live theme will be untouched—work only with unpublished themes and let you verify the changes before you publish it. The support is available 24/7 to help assist you.
Swift’s experts use different techniques to boost the site speed: lazy loading, compressing images, minifying JS & CSS files, optimizing YouTube and Vimeo videos, etc. They can also optimize JavaScript from third parties and external apps.
The app is free to install, but all the optimization services are paid. Unfortunately, Swift only provides custom pricing and doesn’t offer pricing transparency on their listing.