Wordpress isn't bulky because it runs on a database, although you might say that running it with a database in the backend does allow it to be bulky...
The storage medium isn't really what you should be choosing your CMS on, I think. And depending on your required features and expected traffic volumes, I'm not sure there's much need to choose something else.
Sure, other CMS will serve pages faster and handle more visitors better natively... but WP can get you cheap devs fast, rather than casting around for niche workers.
You don't buy a Rolex to tell the time. You buy a Rolex to tell the world.
Mechanically, they're mostly pretty average. But they are a Veblen good for sure, and some people treat them as an investment.
Personally I hate divers/chronos and don't want to lost a significant sum of money when I break one or have one stolen, so I have a nice collection of <$200 quartz watches.
The storage medium isn't really what you should be choosing your CMS on, I think. And depending on your required features and expected traffic volumes, I'm not sure there's much need to choose something else.
Sure, other CMS will serve pages faster and handle more visitors better natively... but WP can get you cheap devs fast, rather than casting around for niche workers.