diff --git a/.env.example b/.env.example
index 67599d7..a07eeae 100644
--- a/.env.example
+++ b/.env.example
@@ -13,4 +13,6 @@ SUPABASE_SECRET_KEY=
 # Optional direct PostgreSQL connection for maintenance. Runtime uses the Supabase API.
 DATABASE_URL=
 MINEGEO_FACE_SIZE=1024
+# Worker heap ceiling in MiB; does not reserve memory or change the web server heap.
+MINEGEO_WORKER_HEAP_MB=4096
 MINEGEO_MAX_UPLOAD_BYTES=268435456
diff --git a/renderer/render.mjs b/renderer/render.mjs
index 001afcd..d69f042 100644
--- a/renderer/render.mjs
+++ b/renderer/render.mjs
@@ -19,6 +19,25 @@ export async function renderSnapshot(
   const server = createServer(async (req, res) => {
     try {
       const url = new URL(req.url, "http://localhost");
+      if (url.pathname === "/terrain.json") {
+        res.setHeader("Content-Type", "application/json");
+        // Avoid Playwright's recursive protocol serialization of millions of
+        // block records. Keep serialization buffers bounded and honor backpressure.
+        const send = async (chunk) => {
+          if (res.destroyed) throw new Error("Terrain connection closed");
+          await new Promise((resolve, reject) => {
+            res.write(chunk, (error) => error ? reject(error) : resolve());
+          });
+        };
+        const { blocks, ...metadata } = snapshot;
+        await send(JSON.stringify(metadata).slice(0, -1) + ',"blocks":[');
+        for (let i = 0; i < blocks.length; i += 2048) {
+          if (signal?.aborted) throw new Error("Rendering cancelled");
+          await send((i ? "," : "") + JSON.stringify(blocks.slice(i, i + 2048)).slice(1, -1));
+        }
+        res.end("]}");
+        return;
+      }
       let path =
         url.pathname === "/three.js"
           ? "node_modules/three/build/three.module.js"
@@ -44,6 +63,7 @@ export async function renderSnapshot(
       );
       res.end(await readFile(path));
     } catch {
+      if (res.headersSent) { res.destroy(); return; }
       res.writeHead(404);
       res.end();
     }
@@ -59,7 +79,11 @@ export async function renderSnapshot(
     page.on("pageerror", (err) => console.error("Renderer:", err.message));
     await page.goto(`http://127.0.0.1:${server.address().port}`);
     await page.waitForFunction(() => window.rendererReady);
-    const stats = await page.evaluate((s) => window.buildTerrain(s), snapshot);
+    const stats = await page.evaluate(async () => {
+      const response = await fetch("/terrain.json");
+      if (!response.ok) throw new Error("Unable to load terrain snapshot");
+      return window.buildTerrain(await response.json());
+    });
     for (const p of viewpoints) {
       if (signal?.aborted) throw new Error("Rendering cancelled");
       await mkdir(`${output}/${p.id}`, { recursive: true });
diff --git a/renderer/scene.js b/renderer/scene.js
index e1aca72..8795fb5 100644
--- a/renderer/scene.js
+++ b/renderer/scene.js
@@ -160,9 +160,12 @@ window.buildTerrain = async (snapshot) => {
   const started = performance.now(),
     batches = new Map(),
     unsupported = new Set();
-  const occupancy = new Map(
-    snapshot.blocks.map((b) => [`${b[0]},${b[1]},${b[2]}`, b[3]]),
-  );
+  const occupancy = new Map();
+  const distinctStates = new Set();
+  for (const b of snapshot.blocks) {
+    occupancy.set(`${b[0]},${b[1]},${b[2]}`, b[3]);
+    distinctStates.add(b[3]);
+  }
   const stateCache = new Map();
   async function stateModels(s) {
     if (stateCache.has(s)) return stateCache.get(s);
@@ -179,7 +182,7 @@ window.buildTerrain = async (snapshot) => {
     return variants;
   }
   // Preload each distinct model once before constructing batched geometry.
-  for (const s of new Set(snapshot.blocks.map((b) => b[3])))
+  for (const s of distinctStates)
     await stateModels(s);
   async function emit(block, m, v = {}) {
     const [bx, by, bz, s] = block;
@@ -310,6 +313,7 @@ window.buildTerrain = async (snapshot) => {
     }
     for (const { m, v } of await stateModels(b[3])) await emit(b, m, v);
   }
+  occupancy.clear();
   for (const batch of batches.values()) {
     const g = new THREE.BufferGeometry();
     g.setAttribute(
@@ -331,6 +335,11 @@ window.buildTerrain = async (snapshot) => {
       opacity: batch.tex.image.src.includes("water") ? 0.8 : 1,
     });
     scene.add(new THREE.Mesh(g, mat));
+    // Drop the JS number arrays as each GPU geometry is completed.
+    batch.positions.length = 0;
+    batch.normals.length = 0;
+    batch.uvs.length = 0;
+    batch.indices.length = 0;
   }
   window.terrainBounds = snapshot.bounds;
   return {
diff --git a/scripts/supervise.mjs b/scripts/supervise.mjs
index 9c0e2d5..db45a8f 100644
--- a/scripts/supervise.mjs
+++ b/scripts/supervise.mjs
@@ -34,4 +34,10 @@ run([
   "--hostname",
   process.env.MINEGEO_HOST || "127.0.0.1",
 ]);
-run(["--import", "tsx", "worker/main.ts"]);
+const workerHeap = Number(process.env.MINEGEO_WORKER_HEAP_MB || 4096);
+if (!Number.isInteger(workerHeap) || workerHeap < 512 || workerHeap > 32768) {
+  console.error("MINEGEO_WORKER_HEAP_MB must be an integer between 512 and 32768.");
+  stop(1);
+} else {
+  run([`--max-old-space-size=${workerHeap}`, "--import", "tsx", "worker/main.ts"]);
+}