From 926c1683d8173955fee75e5cd989c1e49820f6e4 Mon Sep 17 00:00:00 2001
From: Vladlen Grachev <vladlen.grachev@ostrovok.ru>
Date: Thu, 18 Mar 2021 18:18:19 +0300
Subject: [PATCH 1/3] Add _document and _app pre-import

---
 packages/next/next-server/server/next-server.ts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/packages/next/next-server/server/next-server.ts b/packages/next/next-server/server/next-server.ts
index 3f928b43a73fb..0aabdfb8b9abe 100644
--- a/packages/next/next-server/server/next-server.ts
+++ b/packages/next/next-server/server/next-server.ts
@@ -242,6 +242,12 @@ export default class Server {
       this.pagesManifest = require(pagesManifestPath)
     }
 
+    // Modules cache pre-warm speed up initial pages render
+    if (this.pagesManifest && !this._isLikeServerless) {
+      require(join(this.serverBuildDir, this.pagesManifest['/_document']))
+      require(join(this.serverBuildDir, this.pagesManifest['/_app']))
+    }
+
     this.customRoutes = this.getCustomRoutes()
     this.router = new Router(this.generateRoutes())
     this.setAssetPrefix(assetPrefix)

From e1e0c8f38e2b6c86765a3c4cbd0237cfa7b3cf42 Mon Sep 17 00:00:00 2001
From: Vladlen Grachev <vladlen.grachev@ostrovok.ru>
Date: Fri, 23 Jul 2021 10:59:23 +0300
Subject: [PATCH 2/3] Add experimantal prewarmRequiredPages config

---
 packages/next/server/config-shared.ts | 2 ++
 packages/next/server/next-server.ts   | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/next/server/config-shared.ts b/packages/next/server/config-shared.ts
index 3ce60e14da863..723be6476c313 100644
--- a/packages/next/server/config-shared.ts
+++ b/packages/next/server/config-shared.ts
@@ -102,6 +102,7 @@ export type NextConfig = { [key: string]: any } & {
     staticPageGenerationTimeout?: number
     pageDataCollectionTimeout?: number
     isrMemoryCacheSize?: number
+    prewarmRequiredPages?: boolean
   }
 }
 
@@ -169,6 +170,7 @@ export const defaultConfig: NextConfig = {
     pageDataCollectionTimeout: 60,
     // default to 50MB limit
     isrMemoryCacheSize: 50 * 1024 * 1024,
+    prewarmRequiredPages: false,
   },
   future: {
     strictPostcssConfiguration: false,
diff --git a/packages/next/server/next-server.ts b/packages/next/server/next-server.ts
index 918badc90fe4b..79074e14b7922 100644
--- a/packages/next/server/next-server.ts
+++ b/packages/next/server/next-server.ts
@@ -264,7 +264,11 @@ export default class Server {
     }
 
     // Modules cache pre-warm speed up initial pages render
-    if (this.pagesManifest && !this._isLikeServerless) {
+    if (
+      this.nextConfig.experimental.prewarmRequiredPages &&
+      this.pagesManifest &&
+      !this._isLikeServerless
+    ) {
       require(join(this.serverBuildDir, this.pagesManifest['/_document']))
       require(join(this.serverBuildDir, this.pagesManifest['/_app']))
     }

From 9f5b7a3a4157cb32e8d6a73578ae05d78c3ee391 Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Wed, 9 Feb 2022 20:17:43 -0600
Subject: [PATCH 3/3] Add _app and _document pre-import in next-server

---
 packages/next/server/next-server.ts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/packages/next/server/next-server.ts b/packages/next/server/next-server.ts
index 5930a26a6110f..805b0ae016417 100644
--- a/packages/next/server/next-server.ts
+++ b/packages/next/server/next-server.ts
@@ -128,6 +128,17 @@ export default class NextNodeServer extends BaseServer {
         })
       )
     }
+
+    if (!this.renderOpts.dev) {
+      // pre-warm _document and _app as these will be
+      // needed for most requests
+      loadComponents(this.distDir, '/_document', this._isLikeServerless).catch(
+        () => {}
+      )
+      loadComponents(this.distDir, '/_app', this._isLikeServerless).catch(
+        () => {}
+      )
+    }
   }
 
   private compression =