amattoni said

I'm using freestyle on my webpage (CSS in JS solution), and when debugging issues with the console/dev tools open any change to the styles causes the entire style tag to rerender.

Do you mean you are making an edit on the Style Editor pane, or you are making an edit in the Inspector's Rules panel? I do notice coordination among the panels with inline styles, but I haven't paid close attention to the style blocks in the HTML.

Here's another site where you can find a community more focused on the developer tools:

https://discourse.mozilla.org/c/devtools

In this particular case, my code (through freestyle) is adjusting the style tag as the UI updates. I can see jittering and rerendering any time a new rule is added.

Thanks for the link!

Is it this: https://github.com/blakeembrey/free-style

I don't fully understand it, but it sounds as though any time you change a style rule in your script, it could trigger a change to an affected element's class name (hash). Depending on how that switch is made, perhaps there is something like "FOUC".