Did you follow our guide for Elementor:

https://searchandfilter.com/documentation/3rd-party/elementor/

Even if you do not have Masonry enabled (it might not even be an option), use the guide for Masonry & Ajax, but, instead of this code:

(function ( $ ) {
	"use strict";
	
	// detects when the ajax request has finished and the content has been updated
	// re-init the layout scripts from Elementor
	$(document).on("sf:ajaxfinish", ".searchandfilter", function(){
		elementorFrontend.init();
	});
	
}(jQuery));

Use this code:

(function ( $ ) {
	"use strict";
	
	// detects when the ajax request has finished and the content has been updated
	// re-init the layout scripts from Elementor
	$(document).on("sf:ajaxfinish", ".searchandfilter", function(){
		elementorFrontend.hooks.doAction('frontend/element_ready/posts.classic', jQuery('.elementor-widget-posts'));
	});
	
}(jQuery));

Note, if you are placing the code inline on the page (in a widget), it needs the <script>.....</script> tags around it.

Even though you may not have followed the guide section for Masonry and Ajax (maybe you are not using Masonry), did you include the JavaScript I showed in my earlier reply?

The speed with which the results are delivered are a factor of how complex (posts, fields etc) the task is, and the power and efficiency of your server (the physical assets of the server, CPU, memory etc, and the efficiency of the server stack – how well the server software is configured). From within the Search & Filter Pro plugin, there is nothing we can do to aid that.