No. Plug in Speed does not add any JS or CSS files to your code. Instead, it duplicates existing files and minifies the code inside. These minified files will be loaded in place of your originals.
Minification simply removes unnecessary code, such as spaces and comments, inside a code file. This means that the browser will have less to read when loading your site which will always result in a faster load time.
Why is a minified file still shown by Google as causing a speed problem?
Minifying a file is always helpful in reducing its size. However, if the original file is very large to start, it can continue to cause speed issues despite being minified.
To identify which file is causing the problem you will need to look at the file name after pluginspeed.min.
To fully improve the speed at which that file loads you will need to reduce the amount of code inside the original file.
We have noticed that some apps insert very large JS and CSS files into a Shopify theme. You can speed up your shop by removing apps that require large JS files to be loaded on your webpage or reaching out directly to the app's developers.
Not sure which apps are causing your site to be slow? Email us at firstname.lastname@example.org and ask for a free custom speed report.
Please note, that sometimes PageSpeed insights flags core Shopify theme files, such as theme.scss, as being slow. In these cases, there is often nothing that should be done.
Does having two copies of the same file make my site even slower?
No. When a customer views your shop only the duplicated file is loaded by the web browser.
Why not minify the original files?
It is important for developers to have clear spacing and comments inside code files. Without this, they become nearly impossible for a human to read.
Plug in Speed keeps the original JS and CSS files intact so that you can continue easily developing your shop. Any changes made to the original files will also be made automatically in the duplicated files.