diff --git a/packages/docusaurus/src/webpack/base.ts b/packages/docusaurus/src/webpack/base.ts
index c05e022fcf..32e75f3953 100644
--- a/packages/docusaurus/src/webpack/base.ts
+++ b/packages/docusaurus/src/webpack/base.ts
@@ -253,13 +253,6 @@ export async function createBaseConfig({
       modules: ['node_modules', path.join(siteDir, 'node_modules')],
     },
     optimization: {
-      // The optimization.concatenateModules is expensive
-      // - On the server, it's not useful to run it at all
-      // - On the client, it leads to a ~3% JS assets total size decrease
-      //   Let's keep it by default, but large sites may prefer faster builds
-      // See also https://github.com/facebook/docusaurus/pull/11176
-      concatenateModules: !isServer,
-
       // The optimization.mergeDuplicateChunks is expensive
       // - On the server, it's not useful to run it at all
       // - On the client, we compared assets/js before/after and see 0 change
diff --git a/packages/docusaurus/src/webpack/server.ts b/packages/docusaurus/src/webpack/server.ts
index 96454dfb45..740c322c48 100644
--- a/packages/docusaurus/src/webpack/server.ts
+++ b/packages/docusaurus/src/webpack/server.ts
@@ -52,6 +52,16 @@ export default async function createServerConfig({
         color: 'yellow',
       }),
     ],
+    optimization: {
+      // The optimization.concatenateModules is expensive
+      // - On the server, it's not useful to run it at all
+      // - On the client, it leads to a ~3% JS assets total size decrease
+      //   Let's keep it by default, but large sites may prefer faster builds
+      // See also https://github.com/facebook/docusaurus/pull/11176
+      // Note: we don't want to enable it on the client for "docusaurus start"
+      // See also https://github.com/facebook/docusaurus/pull/11222
+      concatenateModules: false,
+    },
   });
 
   return {config, serverBundlePath};