レスポンシブ対応画像の遅延読み込み時に再レンダリングされるのを防止する方法

img {
	width: 400px;
	max-width: 100%;
	height: auto;
}

<div class="imageblock" style="width:400px;">
	<a href="http://theme.1010uzu.com/wp/wp-content/uploads/2017/03/P1040359.jpg" data-size="4000x3000" class="lazy-container" style="padding-bottom:75%;">
		<img data-src="http://theme.1010uzu.com/wp/wp-content/uploads/2017/03/P1040359-400x300.jpg" alt="雲がかかった富士山" 
			width="400" height="300" 
			class="aligncenter size-medium wp-image-252 lazyload" 
			data-srcset="http://theme.1010uzu.com/wp/wp-content/uploads/2017/03/P1040359-400x300.jpg 400w, http://theme.1010uzu.com/wp/wp-content/uploads/2017/03/P1040359-320x240.jpg 320w, http://theme.1010uzu.com/wp/wp-content/uploads/2017/03/P1040359-768x576.jpg 768w, http://theme.1010uzu.com/wp/wp-content/uploads/2017/03/P1040359-800x600.jpg 800w" 
			data-sizes="(max-width: 400px) 100vw, 400px" />
	</a>
</div>

.imageblock{
	max-width: 100%;
}
.lazy-container {
	display: block;
	position: relative;
	height: 0;
	width: 100%;
}

.lazy-container img {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
}

function my_add_padding_image_wrap( $content ) {
	if ( ! preg_match_all( '/<a [^>]+><img [^>]+><\/a>/', $content, $matches_img ) ) {
		return $content;
	}
	$selected_images = array();
	foreach( $matches_img[0] as $image ) {
		if ( strpos( $image, ' width=' ) !== false && strpos( $image, ' height=' ) !== false ) {
			$selected_images[$image] = preg_replace_callback(
						'/(<a [^>]*href=".+?")(><img src=".+?" [^>]* width=")([0-9]*?)(" height=")([0-9]*?)(".*?><\/a>)/',
						function( $matches ){
							return '<div class="imageblock" style="width:' . $matches[3] . 'px;">' . $matches[1] . ' class="lazy-container" style="padding-bottom:'. round( ( $matches[5] / $matches[3] * 100 ), 2 ) . '%;"' . $matches[2] . $matches[3] . $matches[4] . $matches[5] . $matches[6] . '</div>';
						},
						$image
					);
		}
	}
	foreach ( $selected_images as $image => $image_replaced ) {
		$content = str_replace( $image, $image_replaced, $content );
	}
	return $content;
}
add_filter( 'the_content', 'my_add_padding_image_wrap', 9 );