diff --git a/package.json b/package.json
index 36a2dc4fb..435578589 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,7 @@
   "private": true,
   "scripts": {
     "release": "yarn build && yarn changeset publish",
+    "benchmark": "yarn workspace astro run benchmark",
     "build": "yarn build:core",
     "build:core": "lerna run build --scope astro --scope astro-parser",
     "build:vscode": "lerna run build --scope astro-languageserver --scope astro-vscode --scope astro-parser",
diff --git a/packages/astro/src/external.ts b/packages/astro/src/external.ts
new file mode 100644
index 000000000..7a77f7aa3
--- /dev/null
+++ b/packages/astro/src/external.ts
@@ -0,0 +1,42 @@
+import { createRequire } from 'module';
+const require = createRequire(import.meta.url);
+const pkg = require('../package.json');
+
+/**
+ * This file allows us to automatically exclude
+ * particular packages from Snowpack's `esinstall`
+ * step.
+ */
+
+// These packages SHOULD be built by `esinstall`
+const allowList = new Set([
+  'astro-prism',
+  'prismjs',
+  'shorthash'
+]);
+
+const isAstroRenderer = (name: string) => {
+  return name.startsWith(`@astrojs/renderer-`);
+}
+
+// These packages should NOT be built by `esinstall`
+// But might not be explicit dependencies of `astro`
+const denyList = [
+  'prismjs/components/index.js',
+  '@vue/server-renderer'
+];
+
+
+export default Object.keys(pkg.dependencies)
+  // Filter out packages that should be loaded threw Snowpack
+  .filter(name => {
+    // Explicitly allowed packages should NOT be external
+    if (allowList.has(name)) return false;
+    // Astro renderers should NOT be external
+    if (isAstroRenderer(name)) return false;
+    // Everything else SHOULD be external
+    return true;
+  })
+  // Add extras
+  .concat(denyList)
+  .sort();
diff --git a/packages/astro/src/runtime.ts b/packages/astro/src/runtime.ts
index 40d4f5f8b..55f38505b 100644
--- a/packages/astro/src/runtime.ts
+++ b/packages/astro/src/runtime.ts
@@ -13,6 +13,7 @@ import { loadConfiguration, logger as snowpackLogger, startServer as startSnowpa
 import { canonicalURL, stopTimer } from './build/util.js';
 import { debug, info } from './logger.js';
 import { searchForPage } from './search.js';
+import snowpackExternals from './external.js';
 
 interface RuntimeConfig {
   astroConfig: AstroConfig;
@@ -374,7 +375,7 @@ async function createSnowpack(astroConfig: AstroConfig, options: CreateSnowpackO
     },
     packageOptions: {
       knownEntrypoints,
-      external: ['@vue/server-renderer', 'node-fetch', 'prismjs/components/index.js', 'gray-matter'],
+      external: snowpackExternals,
     },
   });
 
diff --git a/packages/astro/test/benchmark/build-cached.json b/packages/astro/test/benchmark/build-cached.json
index 2ddc47c7c..57f8ad38f 100644
--- a/packages/astro/test/benchmark/build-cached.json
+++ b/packages/astro/test/benchmark/build-cached.json
@@ -1,4 +1,4 @@
 {
   "name": "Snowpack Example Build Cached",
-  "time": 10484
-}
+  "time": 8496
+}
\ No newline at end of file
diff --git a/packages/astro/test/benchmark/build-uncached.json b/packages/astro/test/benchmark/build-uncached.json
index ca4f2524a..d7976d926 100644
--- a/packages/astro/test/benchmark/build-uncached.json
+++ b/packages/astro/test/benchmark/build-uncached.json
@@ -1,4 +1,4 @@
 {
   "name": "Snowpack Example Build Uncached",
-  "time": 19629
-}
+  "time": 16200
+}
\ No newline at end of file
diff --git a/packages/astro/test/benchmark/dev-server-cached.json b/packages/astro/test/benchmark/dev-server-cached.json
index e05ffc14c..e28cc05f4 100644
--- a/packages/astro/test/benchmark/dev-server-cached.json
+++ b/packages/astro/test/benchmark/dev-server-cached.json
@@ -1,4 +1,4 @@
 {
   "name": "Snowpack Example Dev Server Cached",
-  "time": 1868
-}
+  "time": 1229
+}
\ No newline at end of file
diff --git a/packages/astro/test/benchmark/dev-server-uncached.json b/packages/astro/test/benchmark/dev-server-uncached.json
index 71601029a..b86393f98 100644
--- a/packages/astro/test/benchmark/dev-server-uncached.json
+++ b/packages/astro/test/benchmark/dev-server-uncached.json
@@ -1,4 +1,4 @@
 {
   "name": "Snowpack Example Dev Server Uncached",
-  "time": 9803
-}
+  "time": 3913
+}
\ No newline at end of file