How can I defer CDN scripts for faster custom theme development?

Technical Q&A
1

Hi Shopify dev community I’m developing a custom theme for my store but at 0.9 second FCP its already very slow :[

I would get full paint at 0.4 seconds (i like) but there’s some render blocking JS slowing down my site that isn’t local to my theme folder. Its some scripts served from shopify CDN but I do not know what they do other then that fact that their (probably) served with any shopify hosted store.

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https://cdn.shopify.com/s/assets/storefront/load_feature-04598b77b1103a920783be825a5f4c245a91397360c621cd772069cf99347113.js
https://cdn.shopify.com/s/assets/shopify_pay/storefront-21b5dddfc8b64c1ad68cee3ba7448d1ffa15c24e969ebc1fbccf1a3784b659ad.js?v=20190107
https://cdn.shopify.com/s/assets/storefront/features-87e8399988880142f2c62771b9d8f2ff6c290b3ff745dd426eb0dfe0db9d1dae.js
https://cdn.shopify.com/s/assets/shop_events_listener-2632023fb2795bd6668b6fbae05b661baba07afb3d62048f023763eca3cd96e3.js
https://cdn.shopify.com/s/javascripts/tricorder/trekkie.storefront.min.js?v=2020.07.13.1

Frankly I find hard to believe that shopify HAS to load 5 different scripts before it can render, so I must defer them.

How do i do?

Thanks Shopify dev community

1 Like
2

bump

3

Hello,

Whereas I totally agree with you, Shopify imposes us at least 500ms of first load JavaScript now (trekkie.js).

And you can’t defer most Js Scripts now anymore, because all scripts are async loaded (but tricorder & trekkie put 500 ms of Javascript evaluation in all your themes).

This is beginning to be too much, way to much of overhead.

4

I have this problem too

5

Agree, it would be nice with a guide on how to resolve this for speed optimization. Trekkie etc may be relevant for convenience, but they often load before the FCP/LCP, causing speed issues.

6

Did you ever find a solution to this?