It is true that loading multiple JavaScript files can slow down loading time of your page/pages. You can manually embed the Instagram posts on WordPress pages since embedding Instagram posts are now supported.
On your browser, locate the Instagram post that you want to include on your page. Copy the link on the browser’s address bar and paste it directly on the WordPress post. It will automatically generate a preview for you. Repeat this for the rest of the posts.
^P
I apologize, I misunderstood the context. This is the only way to embed the Instagram posts. The “embeds.js” you are referring to is an Instagram file. Without it, Instagram posts can’t be embedded.
I recommend using BJ Lazy Load. The plug-in is lightweight. It replaces all your post images, thumbnails and iframes with a placeholder and loads the content as it gets close to enter the browser window when the visitor scrolls the page. This should help load your pages faster.