In what might be the best example of bad practice I've ever found in my history of working with WordPress, a client asked me to deal with slow page loads by deleting some un-needed auto-loading options.

This included layout options for a WP theme they hadn't used in years.

The theme stored each layout option in a different row in the wp_options table. Each of those rows was loaded every time WordPress served a page.

There were THIRTEEN THOUSAND rows comprising 5.85 MB of data.