Last week, I have updated a new theme(Shella theme) for the live store. After went live my site speed is getting decreased day-by-day. Now my site score is only 22.
But last week it has shown a 60+ score. My old theme(Debut theme) given the best performance.
Can anyone explain how the Shopify score is calculated? I have tested my site in Google page insights. it has given the best results compared to the Shopify score(22).
And I want to know with the new theme how much I can able to increase the results?
Shopify generates that score by aggregating the overall pagespeed score of your various templates.
Shell theme has some implementation of pagespeed improvements, like it's resources are not render blocking, but it has really bad performance in other aspects.
For instance, it has horrible CLS on the product pages, and bad LCP.
Since Shopify takes your average score, if your product pages or other pages are bad, that will drag down the overall score displayed by Shopify.
Shopify takes the average score from 3 pages: the home page, the collections page, and the product with the most traffic in the last 7 days.
Most likely, the rating on the product and collections page spoils the overall rating.
The decline in the rating depends on many factors. You may have installed apps or added media resources. In particular, the video. Or, initially, the theme itself had a good rating on the main page, but they did not pay enough attention to the rest of the important pages.
Take a look at our article, your case is similar to our example. Here you can find the link to our article: https://speedimize.io/blog/speed-store-improvement
Hope this information will be useful to you.