Couple things, I suggest leaving the Settings properties as they are or you'll mess up the rest of the site's performance.
On your "custom" web part:
- remove any custom caching API code
- set the partial cache dependencies property to 0
- ensure you custom code is implemented properly in the web part, meaning you're not loading data on the page load or pre-render. You need to implement it like the other web parts have it implemented or like the documentation shows.