diff --git a/source/npm/qsharp/package.json b/source/npm/qsharp/package.json
index 46ba3ee1dc7..fb76ec65d18 100644
--- a/source/npm/qsharp/package.json
+++ b/source/npm/qsharp/package.json
@@ -24,6 +24,8 @@
     "./katas-md": "./dist/katas-md.js",
     "./state-viz": "./ux/circuit-vis/state-viz/worker/index.ts",
     "./ux": "./ux/index.ts",
+    "./ux/bloch": "./ux/bloch/index.ts",
+    "./ux/chem": "./ux/chem/index.tsx",
     "./qdk-theme.css": "./ux/qdk-theme.css",
     "./rz-array.json": "./rz-array.json"
   },
diff --git a/source/npm/qsharp/ux/bloch/index.ts b/source/npm/qsharp/ux/bloch/index.ts
new file mode 100644
index 00000000000..209269d344b
--- /dev/null
+++ b/source/npm/qsharp/ux/bloch/index.ts
@@ -0,0 +1,7 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+// Dedicated entry point for the Bloch sphere widget. Keeping this behind its
+// own package subpath (qsharp-lang/ux/bloch) isolates three.js to a lazily
+// loaded chunk instead of bundling it into the main ux barrel.
+export { BlochSphere, type BlochSphereProps } from "./bloch.js";
diff --git a/source/npm/qsharp/ux/index.ts b/source/npm/qsharp/ux/index.ts
index 709b29bb9f4..d30dd70ac6a 100644
--- a/source/npm/qsharp/ux/index.ts
+++ b/source/npm/qsharp/ux/index.ts
@@ -20,11 +20,9 @@ export { SpaceChart } from "./spaceChart.js";
 export { ScatterChart } from "./scatterChart.js";
 export { EstimatesOverview } from "./estimatesOverview.js";
 export { EstimatesPanel } from "./estimatesPanel.js";
-export { BlochSphere } from "./bloch/bloch.js";
 export { Circuit, CircuitPanel } from "./circuit.js";
 export { setRenderer, Markdown } from "./renderers.js";
 export { Atoms, type ZoneLayout, type TraceData } from "./atoms/index.js";
-export { MoleculeViewer } from "./chem/index.js";
 export { Entanglement, type EntanglementProps } from "./entanglement.js";
 export {
   ensureTheme,
diff --git a/source/playground/src/main.tsx b/source/playground/src/main.tsx
index 804fa55c5ee..41a8362fff4 100644
--- a/source/playground/src/main.tsx
+++ b/source/playground/src/main.tsx
@@ -49,7 +49,8 @@ import {
 // Set up the Markdown renderer with KaTeX support
 import mk from "@vscode/markdown-it-katex";
 import markdownIt from "markdown-it";
-import { setRenderer, BlochSphere } from "qsharp-lang/ux";
+import { setRenderer } from "qsharp-lang/ux";
+import { BlochSphere } from "qsharp-lang/ux/bloch";
 
 const md = markdownIt("commonmark");
 md.use((mk as any).default, {
diff --git a/source/vscode/build.mjs b/source/vscode/build.mjs
index 7fee3349eed..cead55a5365 100644
--- a/source/vscode/build.mjs
+++ b/source/vscode/build.mjs
@@ -11,7 +11,13 @@ import { build as esbuildBuild, context } from "esbuild";
 const thisDir = dirname(fileURLToPath(import.meta.url));
 const libsDir = join(thisDir, "..", "..", "node_modules");
 
-// ── Shared esbuild options ──────────────────────────────────────────
+// Watch builds skip minification so rebuilds stay fast and stack traces stay
+// readable during development. One-shot builds (CI and `build.py`) minify to
+// keep the shipped webview/extension bundles small. Linked source maps are
+// emitted either way, so minified output remains debuggable.
+const isWatch = process.argv.includes("--watch");
+
+// ── Shared esbuild options ──────────────────────────────────────
 
 /** @type {import("esbuild").BuildOptions} */
 const commonBuildOptions = {
@@ -20,6 +26,7 @@ const commonBuildOptions = {
   format: "cjs",
   target: ["es2022"],
   sourcemap: "linked",
+  minify: !isWatch,
 };
 
 // ── Per-platform build options ──────────────────────────────────────
@@ -32,7 +39,6 @@ const platformBuildOptions = {
     outbase: join(thisDir, "src"),
     outdir: join(thisDir, "out"),
     entryPoints: [
-      join(thisDir, "src", "webview/webview.tsx"),
       join(thisDir, "src", "webview/editor.tsx"),
       join(thisDir, "src", "learning/webview/webview-client.tsx"),
     ],
@@ -42,6 +48,25 @@ const platformBuildOptions = {
     },
     // plugins added at build time (needs inlineStateComputeWorkerPlugin)
   },
+  // The main webview bundle is built as ESM with code splitting enabled so
+  // that heavy, rarely-used dependencies (e.g. three.js used only by the
+  // Bloch sphere) are emitted as separate chunks that are loaded on demand
+  // via dynamic import(), rather than bloating the shared webview.js.
+  webview: {
+    ...commonBuildOptions,
+    format: "esm",
+    splitting: true,
+    platform: "browser",
+    outbase: join(thisDir, "src"),
+    outdir: join(thisDir, "out"),
+    chunkNames: "webview/chunks/[name]-[hash]",
+    entryPoints: [join(thisDir, "src", "webview/webview.tsx")],
+    define: {
+      "import.meta.url": "undefined",
+      __PLATFORM__: JSON.stringify("browser"),
+    },
+    // plugins added at build time (needs inlineStateComputeWorkerPlugin)
+  },
   browser: {
     ...commonBuildOptions,
     entryPoints: [
@@ -209,8 +234,8 @@ async function buildPlatform(platform) {
   const options = platformBuildOptions[platform];
   if (!options) throw new Error(`Invalid platform: ${platform}`);
 
-  // UI build needs the inline worker plugin
-  if (platform === "ui") {
+  // UI builds need the inline worker plugin
+  if (platform === "ui" || platform === "webview") {
     options.plugins = [inlineStateComputeWorkerPlugin];
   }
 
@@ -272,8 +297,6 @@ export async function watchVsCode() {
 (async () => {
   const thisFilePath = resolve(fileURLToPath(import.meta.url));
   if (thisFilePath === resolve(process.argv[1])) {
-    const isWatch = process.argv.includes("--watch");
-
     if (isWatch) {
       await watchVsCode();
     } else {
@@ -282,6 +305,7 @@ export async function watchVsCode() {
 
       await Promise.all([
         buildPlatform("ui"),
+        buildPlatform("webview"),
         buildPlatform("browser"),
         buildPlatform("node"),
         buildPlatform("node-worker"),
diff --git a/source/vscode/src/webview/webview.tsx b/source/vscode/src/webview/webview.tsx
index 7f7f0d0f615..aba03cf0143 100644
--- a/source/vscode/src/webview/webview.tsx
+++ b/source/vscode/src/webview/webview.tsx
@@ -6,12 +6,12 @@
 const vscodeApi = acquireVsCodeApi();
 
 import { render } from "preact";
+import { lazy, Suspense } from "preact/compat";
 import {
   CircuitPanel,
   CircuitProps,
   EstimatesPanel,
   Histogram,
-  BlochSphere,
   setRenderer,
   detectThemeChange,
   updateStyleSheetTheme,
@@ -21,6 +21,13 @@ import { HelpPage } from "./help";
 import { DocumentationView, IDocFile } from "./docview";
 import "./webview.css";
 
+// The Bloch sphere pulls in three.js, which is large and only needed when a
+// Bloch sphere view is actually opened. Load it lazily via a dynamic import so
+// esbuild emits it (and three.js) as a separate chunk kept out of webview.js.
+const BlochSphere = lazy(() =>
+  import("qsharp-lang/ux/bloch").then((m) => ({ default: m.BlochSphere })),
+);
+
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-ignore - there are no types for this
 import mk from "@vscode/markdown-it-katex";
@@ -234,7 +241,11 @@ function App({ state }: { state: State }) {
     case "help":
       return <HelpPage />;
     case "bloch":
-      return <BlochSphere />;
+      return (
+        <Suspense fallback={<div>Loading...</div>}>
+          <BlochSphere />
+        </Suspense>
+      );
     case "documentation":
       // Ideally we'd have this on all web views, but it makes the font a little
       // too large in the others right now. Something to unify later.
diff --git a/source/vscode/src/webviewPanel.ts b/source/vscode/src/webviewPanel.ts
index 58ab0159754..dfda7a5e864 100644
--- a/source/vscode/src/webviewPanel.ts
+++ b/source/vscode/src/webviewPanel.ts
@@ -363,7 +363,7 @@ export class QSharpWebViewPanel {
       <link rel="stylesheet" href="${githubCss}" />
       <link rel="stylesheet" href="${katexCss}" />
       <link rel="stylesheet" href="${webviewCss}" />
-      <script src="${webviewJs}"></script>
+      <script type="module" src="${webviewJs}"></script>
       <script>
         window.resourcesUri = "${resourcesUri.toString()}";
       </script>
diff --git a/source/widgets/js/index.tsx b/source/widgets/js/index.tsx
index 012fd0676dd..da8cdbe5fb5 100644
--- a/source/widgets/js/index.tsx
+++ b/source/widgets/js/index.tsx
@@ -15,10 +15,10 @@ import {
   Atoms,
   type ZoneLayout,
   type TraceData,
-  MoleculeViewer,
   Entanglement,
   type EntanglementProps,
 } from "qsharp-lang/ux";
+import { MoleculeViewer } from "qsharp-lang/ux/chem";
 import markdownIt from "markdown-it";
 import "./widgets.css";