Ask HN: Why does 'View Source' issue a new HTTP request?
It's a bug: https://bugzilla.mozilla.org/show_bug.cgi?id=307089Or, it's a memory saving feature. To implement "View source from cache" requires keeping around the raw page HTML, which you might not otherwise need after parsing - except you probably will for all the developer tools to work, so this  probably should just be considered bug.