Hi, we faced the same issue that 3rd party apps loaded a lot of Javascript on every page, even tho the apps were sometimes only required on specific pages like cart, cms etc.
We developed an app that helps to manage where to load 3rd party Javascripts and where to block it.
https://apps.shopify.com/pagespeed-javascript
The app is still in an early stage and if you have any suggestions please let me know
