Welcome aboard shenanigans.
If this is a new site, please take a step back and consider something.
What happens if "some-page.html" gets indexed in the search engines and someone clicks a link to it?
The page displays out of context of the frameset without navigation back to your site.
Some things may have changed over the years that make this irrelevant, but I don't think so . . .
There are two really good ways to avoid this. The first is Server Side Includes (SSI) and requires no programming. The second is to use PHP includes, with a global header include. SSI requires no programming experience, but basic PHP with header includes is simple to learn as well.
Both give you the same result as a frameset, one file to edit to modify navigation, minus the problem mentioned. Additionally when you click links, the address bar changes, which makes it easier for users to bookmark and remember URL's (although browsers have come a way in that regard, bookmarking a framed page usually gets the correct framed pages.) Both are so easy to implement there is no real reason to use frames.
Yes the banner will reload on every page, but as mentioned, you need to optimize it and it will cease to be an issue. The benefits far outweigh the savings in load time.