optimise each blocks

packages/svelte/src/compiler/phases/3-transform/server/transform-server.js

@@ -1392,13 +1392,8 @@ const template_visitors = {
 			each.push(b.let(node.index, index));
 		}
 
-		// TODO we shouldn't need these
-		each.push(b.stmt(b.assignment('+=', b.id('$$payload.out'), b.literal('<!--#each-item-->'))));
-
 		each.push(.../** @type {import('estree').BlockStatement} */ (context.visit(node.body)).body);
 
-		each.push(b.stmt(b.assignment('+=', b.id('$$payload.out'), b.literal('<!--/each-item-->'))));
-
 		const for_loop = b.for(
 			b.let(index, b.literal(0)),
 			b.binary('<', index, b.member(array_id, b.id('length'))),

packages/svelte/src/internal/client/dom/blocks/each.js

@@ -181,10 +181,7 @@ export function each(anchor, flags, get_collection, get_key, render_fn, fallback
 			var item;
 
 			for (var i = 0; i < length; i++) {
-				if (
-					child_anchor.nodeType !== 8 ||
-					/** @type {Comment} */ (child_anchor).data !== '#each-item'
-				) {
+				if (child_anchor.nodeType === 8 && /** @type {Comment} */ (child_anchor).data === '/each') {
 					// If `nodes` is null, then that means that the server rendered fewer items than what
 					// expected, so break out and continue appending non-hydrated items
 					anchor = /** @type {Comment} */ (child_anchor);
@@ -193,15 +190,13 @@ export function each(anchor, flags, get_collection, get_key, render_fn, fallback
 					break;
 				}
 
-				hydrate_next();
-
 				var value = array[i];
 				var key = get_key(value, i);
 				item = create_item(child_anchor, state, prev, null, value, key, i, render_fn, flags);
 				state.items.set(key, item);
 				var close = hydrate_node.nextSibling; // TODO validate. or replace `<!--]--><!--[-->` with `<!---->`
 				// hydrate_next();
-				child_anchor = /** @type {Comment} */ (hydrate_next());
+				child_anchor = /** @type {Comment} */ (hydrate_node);
 
 				prev = item;
 			}

packages/svelte/tests/snapshot/samples/each-string-template/_expected/server/index.svelte.js

@@ -8,9 +8,7 @@ export default function Each_string_template($$payload) {
 	for (let $$index = 0; $$index < each_array.length; $$index++) {
 		const thing = each_array[$$index];
 
-		$$payload.out += "<!--#each-item-->";
 		$$payload.out += `${$.escape(thing)}, `;
-		$$payload.out += "<!--/each-item-->";
 	}
 
 	$$payload.out += `<!--/each-->`;