From 121cd886a4fa2304c8b70e8c87d31d9516559c39 Mon Sep 17 00:00:00 2001
From: David Taylor <david@taylorhq.com>
Date: Mon, 21 Aug 2023 13:42:59 +0100
Subject: [PATCH] PERF: Improve rendering performance of empty PluginOutlets
 (#23165)

This commit introduces a 'shortcut' when rendering PluginOutlets which have no registered connectors. On my machine, this improves rendering performance of empty PluginOutlets by around 30-40% (tested by running tachometer on a `/latest` route with 600 plugin outlets).
---
 .../javascripts/discourse/app/components/plugin-outlet.hbs | 2 +-
 .../javascripts/discourse/app/components/plugin-outlet.js  | 5 +++++
 .../javascripts/discourse/app/lib/plugin-connectors.js     | 7 +++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/app/assets/javascripts/discourse/app/components/plugin-outlet.hbs b/app/assets/javascripts/discourse/app/components/plugin-outlet.hbs
index 2639a58e88a..acf2e087f05 100644
--- a/app/assets/javascripts/discourse/app/components/plugin-outlet.hbs
+++ b/app/assets/javascripts/discourse/app/components/plugin-outlet.hbs
@@ -22,7 +22,7 @@
       {{/if}}
     {{/each}}
   </this.wrapperComponent>
-{{else}}
+{{else if this.connectorsExist}}
   {{! The modern path: no wrapper element = no classic component }}
   {{#each this.connectors as |c|}}
     {{#if c.componentClass}}
diff --git a/app/assets/javascripts/discourse/app/components/plugin-outlet.js b/app/assets/javascripts/discourse/app/components/plugin-outlet.js
index 840c8b73f32..0fc1af240fb 100644
--- a/app/assets/javascripts/discourse/app/components/plugin-outlet.js
+++ b/app/assets/javascripts/discourse/app/components/plugin-outlet.js
@@ -3,6 +3,7 @@ import ClassicComponent from "@ember/component";
 
 import {
   buildArgsWithDeprecations,
+  connectorsExist,
   renderedConnectorsFor,
 } from "discourse/lib/plugin-connectors";
 import { helperContext } from "discourse-common/lib/helpers";
@@ -86,6 +87,10 @@ export default class PluginOutletComponent extends GlimmerComponentWithDeprecate
     );
   }
 
+  get connectorsExist() {
+    return connectorsExist(this.args.name);
+  }
+
   // Traditionally, pluginOutlets had an argument named 'args'. However, that name is reserved
   // in recent versions of ember so we need to migrate to outletArgs
   @cached
diff --git a/app/assets/javascripts/discourse/app/lib/plugin-connectors.js b/app/assets/javascripts/discourse/app/lib/plugin-connectors.js
index 2a7e1411f8a..8960ab848b7 100644
--- a/app/assets/javascripts/discourse/app/lib/plugin-connectors.js
+++ b/app/assets/javascripts/discourse/app/lib/plugin-connectors.js
@@ -165,6 +165,13 @@ function buildConnectorCache() {
   }
 }
 
+export function connectorsExist(outletName) {
+  if (!_connectorCache) {
+    buildConnectorCache();
+  }
+  return Boolean(_connectorCache[outletName]);
+}
+
 export function connectorsFor(outletName) {
   if (!_connectorCache) {
     buildConnectorCache();