In the above example, the /leo-docsupport/ page is about 70kb in size. Once loaded, the browser would normally go out and start loading scripts, CSS files, and more. For this page, it's about 1.3 MB transferred.
When you view the same page with Speedreader, you load only the first 70kb. Brave then reshapes that response to isolate only the key data (i.e., the article). Speedreader is intelligent enough to identify images which also need to be included, and pulls those in as well. For this page, that's 4 files loaded (i.e., the page, and 3 in-situ images) compared to the standard view which includes over 10x more files.