I've added json-ld structured data to my website, which caused the page size to increase from 80kb to 120kb, this hurts the page load speed as well as decreases the text to code ratio. Is there a better way to provide structured data, not including it in the html directly?
Let me try to answer this question.
I don't think you can add your json-ld structured data on external source like javascript or css, but you can try to move up your json-ld structured data from your header into your footer of your web page.
SEO Quake chrome extension doesn't give a warning for this kind of implementation.
I hope this can help up you to increase your page load speed but maybe still a weak answer because of the text to code ratio won't be decreased as per your question.