WS Form is designed with form-rendering performance in mind. In WordPress, published forms are rendered from a pre-compiled snapshot that uses a single database query per rendering.
Form submissions are stored separately from standard WordPress database tables. This helps avoid adding submission records to tables used by pages, posts, and attachments.
WS Form also keeps front-end output lean. Most fields use native browser functionality, scripts and CSS are only enqueued when a form is rendered, and additional libraries are only loaded when a form contains a field type that needs them.