Hello, @Marta,
You can deactivate the Elementor and test the site speed then.
“CRITICAL Allowed memory size of 268435456 bytes exhausted (tried to allocate 49152 bytes) en /homepages/20/d587399487/htdocs/nuevo/wp-includes/class-wpdb.php en la línea 2153 ” – contact your hosting provider and ask to fix this error.
Kind Regards,
8theme team