Every option with autoload = yes is fetched in a single query on every request and held in memory for the whole of it. That is the right default for a setting read on most pages and a bad one for a cached API response that is read on one.
// autoloaded — third argument defaults to 'yes'
add_option( 'my_plugin_settings', $settings );
// not autoloaded
add_option( 'my_plugin_api_cache', $blob, '', 'no' );The cost is invisible because it is one query either way; what grows is the size of its result. A site with a few plugins storing serialised blobs can reach several megabytes of autoloaded options, unserialised on every request including AJAX and cron. Check it before assuming it is fine — the query that lists the largest ones takes ten seconds to write and frequently finds something surprising.