From 44f6acec774eafc6cba21c84dc4d8fbc002c1128 Mon Sep 17 00:00:00 2001
From: agentic-sanyam <264568151+agentic-sanyam@users.noreply.github.com>
Date: Sat, 28 Feb 2026 20:00:37 +0530
Subject: [PATCH] Perf: Memoize Render plugin's compile functions (#3915)

---
 src/Plugins/RenderPlugin.js      | 41 +++++++++++++++++++++--
 test/TemplateRenderPluginTest.js | 56 ++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+), 3 deletions(-)

diff --git a/src/Plugins/RenderPlugin.js b/src/Plugins/RenderPlugin.js
index 0da8c6a75..ad1bc4c71 100644
--- a/src/Plugins/RenderPlugin.js
+++ b/src/Plugins/RenderPlugin.js
@@ -15,6 +15,9 @@ import Liquid from "../Adapters/Engines/Liquid.js";
 
 class EleventyNunjucksError extends EleventyBaseError {}
 
+const compileCache = new WeakMap();
+const compileFileCache = new WeakMap();
+
 /** @this {object} */
 async function compile(content, templateLang, options = {}) {
 	let { templateConfig, extensionMap } = options;
@@ -31,6 +34,15 @@ async function compile(content, templateLang, options = {}) {
 		templateLang = this.page.templateSyntax;
 	}
 
+	if (!compileCache.has(templateConfig)) {
+		compileCache.set(templateConfig, new Map());
+	}
+	let projectCache = compileCache.get(templateConfig);
+	let cacheKey = `${content}###${templateLang || ""}`;
+	if (projectCache.has(cacheKey)) {
+		return projectCache.get(cacheKey);
+	}
+
 	if (!extensionMap) {
 		if (strictMode) {
 			throw new Error("Internal error: missing `extensionMap` in RenderPlugin->compile.");
@@ -62,7 +74,9 @@ async function compile(content, templateLang, options = {}) {
 		);
 	}
 
-	return tr.getCompiledTemplate(content);
+	let fn = await tr.getCompiledTemplate(content);
+	projectCache.set(cacheKey, fn);
+	return fn;
 }
 
 // No templateLang default, it should infer from the inputPath.
@@ -94,6 +108,12 @@ async function compileFile(inputPath, options = {}, templateLang) {
 		);
 	}
 
+	if (!compileFileCache.has(templateConfig)) {
+		compileFileCache.set(templateConfig, new Map());
+	}
+	let projectCache = compileFileCache.get(templateConfig);
+	let cacheKey = `${normalizedPath}###${templateLang || ""}`;
+
 	if (!extensionMap) {
 		if (strictMode) {
 			throw new Error("Internal error: missing `extensionMap` in RenderPlugin->compileFile.");
@@ -112,12 +132,27 @@ async function compileFile(inputPath, options = {}, templateLang) {
 	}
 
 	if (!tr.engine.needsToReadFileContents()) {
-		return tr.getCompiledTemplate(null);
+		let fn = await tr.getCompiledTemplate(null);
+		// Note: we don't cache these yet, but we could.
+		return fn;
 	}
 
 	// TODO we could make this work with full templates (with front matter?)
 	let content = readFileSync(inputPath, "utf8");
-	return tr.getCompiledTemplate(content);
+
+	if (projectCache.has(cacheKey)) {
+		let cached = projectCache.get(cacheKey);
+		if (cached.content === content) {
+			return cached.fn;
+		}
+	}
+
+	let fn = await tr.getCompiledTemplate(content);
+	projectCache.set(cacheKey, {
+		content,
+		fn,
+	});
+	return fn;
 }
 
 /** @this {object} */
diff --git a/test/TemplateRenderPluginTest.js b/test/TemplateRenderPluginTest.js
index 2a073adcb..1d269e6d0 100644
--- a/test/TemplateRenderPluginTest.js
+++ b/test/TemplateRenderPluginTest.js
@@ -1,4 +1,5 @@
 import test from "ava";
+import fs from "node:fs";
 
 import {
   default as RenderPlugin,
@@ -7,9 +8,12 @@ import {
   RenderManager,
 } from "../src/Plugins/RenderPlugin.js";
 import Eleventy from "../src/Eleventy.js";
+import TemplateConfig from "../src/TemplateConfig.js";
+import ProjectDirectories from "../src/Util/ProjectDirectories.js";
 
 import { normalizeNewLines } from "./Util/normalizeNewLines.js";
 
+
 async function getTestOutput(input, configCallback = function () {}) {
   let elev = new Eleventy(input, "./_site/", {
     config: function (eleventyConfig) {
@@ -321,3 +325,55 @@ test("#3368 #3810 config init bug with RenderManager", async (t) => {
   let results = await elev.toJSON();
   t.is(results[0].content, `<h1>Sign up for our newsletter!</h1>`);
 });
+
+async function getSharedConfig() {
+  let templateConfig = new TemplateConfig(null, false);
+  templateConfig.setDirectories(new ProjectDirectories());
+  await templateConfig.init();
+  return templateConfig;
+}
+
+test("Verify compileFile returns the same function with memoization (shared config)", async (t) => {
+  const filePath = "./test/stubs-render-plugin/11tyjs-file.njk";
+  let templateConfig = await getSharedConfig();
+  let options = { templateConfig };
+
+  let fn1 = await RenderPluginFile(filePath, options);
+  let fn2 = await RenderPluginFile(filePath, options);
+
+  t.is(fn1, fn2);
+});
+
+test("Verify compileFile returns different functions for different content (shared config)", async (t) => {
+  const filePath = "./test/stubs-render-plugin/temp-file.njk";
+  fs.writeFileSync(filePath, "content 1");
+
+  let templateConfig = await getSharedConfig();
+  let options = { templateConfig };
+
+  let fn1 = await RenderPluginFile(filePath, options);
+
+  fs.writeFileSync(filePath, "content 2");
+  let fn2 = await RenderPluginFile(filePath, options);
+
+  t.not(fn1, fn2);
+
+  if (fs.existsSync(filePath)) {
+    fs.unlinkSync(filePath);
+  }
+});
+
+test("Verify compile (string) returns the same function with memoization (shared config)", async (t) => {
+  let templateConfig = await getSharedConfig();
+  let options = { templateConfig };
+  const content = "Hello {{ name }}";
+
+  // Need to mock this.page.templateSyntax if templateLang is not passed
+  const context = { page: { templateSyntax: "njk" } };
+
+  let fn1 = await RenderPluginString.call(context, content, "njk", options);
+  let fn2 = await RenderPluginString.call(context, content, "njk", options);
+
+  t.is(fn1, fn2);
+});
+