lazy load media content

closes #54

theme/templates/macros/content_renderer.html

@@ -64,7 +64,7 @@
 				{%- set ns.url = [siteurl, ns.url]|join("/") -%}
 			{%- endif -%}
 		{%- endif -%}
-		<img {{ render_attr(attr, lang, extra={"src": ns.url, "title": {"value":title, "escape": true}}) }} alt="
+		<img {{ render_attr(attr, lang, extra={"src": ns.url, "title": {"value":title, "escape": true}, "loading": "lazy"}) }} alt="
 			{%- if alt is string -%}
 				{{ alt|e }}
 			{%- else -%}

theme/templates/macros/renderers.html

@@ -24,7 +24,7 @@
 {%- endmacro -%}
 
 {%- macro section_iframe(s, lang) -%}
-	<iframe src="{{ s.url }}"></iframe>
+	<iframe src="{{ s.url }}" loading="lazy"></iframe>
 {%- endmacro -%}
 
 {%- macro section_tag(s, lang) -%}