Until Figma pursues changes to the resource panel, we have just enough information and tools to be careful about our file size. I’ve replied to a related thread listing the 5 things you can do to reduce resource use ordered by impact.
Along with this, I use Alex Wang’s Layer Counter plugin that breaks down layers by type: (vectors, image, shapes, frames, groups, instances, etc). This helps me ensure components (and subsequently their instances) are as lightweight as possible.