public function _async_content_images( $content ) {
		if ( ! $this->_is_async_content_images() ) {
			return $content;
		}

		if ( ! preg_match_all( '/<img [^>]+>/', $content, $matches ) ) {
			return $content;
		}

		$selected_images = [];
		foreach ( $matches[0] as $image ) {
			if ( false === strpos( $image, ' decoding=' ) && preg_match( '/wp-image-([0-9]+)/i', $image, $reg ) ) {
				$selected_images[ $reg[1] ][] = $image;
			}
		}

		foreach ( $selected_images as $image_id => $images ) {
			foreach ( $images as $image ) {
				$new_image = $this->_add_decoding_to_content_image( $image );
				$new_image = $this->_add_data_src_to_content_image( $new_image, $image_id );
				$new_image = $this->_add_data_srcset_to_content_image( $new_image, $image_id );

				$content = str_replace( $image, $new_image, $content );
			}
		}

		return $content;
	}