chore: improve runtime overhead of creating comment templates (#11591)

* chore: improve runtime overhead of creating comment templates

* Update packages/svelte/src/internal/client/dom/template.js

Co-authored-by: Simon H <[email protected]>

* changeset

---------

Co-authored-by: Simon H <[email protected]>
Co-authored-by: Rich Harris <[email protected]>

Author: 3 people

.changeset/eighty-lizards-notice.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+chore: improve runtime overhead of creating comment templates

packages/svelte/src/internal/client/dom/template.js

@@ -251,7 +251,18 @@ export function text(anchor) {
 	return push_template_node(node);
 }
 
-export const comment = template('<!>', TEMPLATE_FRAGMENT | TEMPLATE_USE_IMPORT_NODE);
+export function comment() {
+	// we're not delegating to `template` here for performance reasons
+	if (hydrating) {
+		return push_template_node(hydrate_nodes);
+	}
+	var frag = document.createDocumentFragment();
+	var anchor = empty();
+	frag.append(anchor);
+	push_template_node([anchor]);
+
+	return frag;
+}
 
 /**
  * Assign the created (or in hydration mode, traversed) dom elements to the current block