You can disable initial directory or have results only after search under Experience/Results if you have the Experience add-on.
If your configuration or server is not responding fast enough I am not sure there is anything SLP will be able to do.
See additional information for shortcodes in documentation
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You have not shown your screenshot or provided us with enough information to assist you. what version of SLP are you using , what version of WP , what version or add-ons, what is your site url, php? version php, there are numerous articles from the developer and author about information technology improving your site, boosting server, configuration etc,
see the side menu under INFO and NEWS