gistfile1.txt

// Add to theme functions.php
// Removes lazy loading from the first image of the slider
function rs_disable_first_lazy_image($out) {
	$url = preg_match('/<a class="rsImg" href="(.+)">(.+)<\/a>/', $out, $match);

	if ( empty($match[1]) ) {
		return $out;
	}

	$alt = '';
	if ( !empty($match[2]) ) {
		$alt = esc_attr($match[2]);
	}

	$first_img_html = '<img class="rsImg" src="'. esc_attr($match[1]) .'" alt="'.$alt.'"/>';

	return preg_replace('/<a class="rsImg"(.+)<\/a>/', $first_img_html, $out, 1);
}
add_filter('new_rs_slides_output_before_end', 'rs_disable_first_lazy_image', 10, 4);