diff --git a/.cargo/config.toml b/.cargo/config.toml
deleted file mode 100644
index c316f0961..000000000
--- a/.cargo/config.toml
+++ /dev/null
@@ -1,2 +0,0 @@
-[target.wasm32-unknown-unknown]
-rustflags=["--cfg=web_sys_unstable_apis"]
diff --git a/web/packages/core/package.json b/web/packages/core/package.json
index c74082bad..e759687c2 100644
--- a/web/packages/core/package.json
+++ b/web/packages/core/package.json
@@ -9,15 +9,30 @@
         "pkg/"
     ],
     "scripts": {
-        "build": "npm run build:cargo && npm run build:wasm-bindgen && npm run build:wasm-opt && npm run build:ts",
+        "build": "npm run build:ruffle_web && npm run build:ruffle_web-wasm_extensions && npm run build:ts",
+
+        "//1": "# Unfortunately, we have to set $RUSTFLAGS here, instead of in .cargo/config.toml (for example), because it's not possible to specify them per-profile; see cargo issue #7878.",
+        "//2": "# Enabling 'build-std' would also be great, but it's not stable yet.",
+
+        "build:ruffle_web": "cross-env OUT_NAME=ruffle_web RUSTFLAGS=\"--cfg=web_sys_unstable_apis\" npm run build:cargo_bindgen_opt",
+        "build:ruffle_web-wasm_extensions": "echo \"Building module with WebAssembly extensions\" && cross-env OUT_NAME=ruffle_web-wasm_extensions RUSTFLAGS=\"--cfg=web_sys_unstable_apis -C target-feature=+bulk-memory,+simd128,+nontrapping-fptoint,+sign-ext\" npm run build:cargo_bindgen_opt",
+
+        "//3": "# This just chains together the three commands after it.",
+        "build:cargo_bindgen_opt": "npm run build:cargo && npm run build:wasm-bindgen && npm run build:wasm-opt",
+
         "build:cargo": "cross-env-shell \"cargo build --release --target wasm32-unknown-unknown --features \\\"$CARGO_FEATURES\\\"\"",
-        "build:wasm-bindgen": "wasm-bindgen ../../../target/wasm32-unknown-unknown/release/ruffle_web.wasm --target web --out-dir ./pkg --out-name ruffle_web",
-        "build:wasm-opt": "wasm-opt -o ./pkg/ruffle_web_bg.wasm -O -g ./pkg/ruffle_web_bg.wasm || npm run build:wasm-opt-failed",
+        "build:wasm-bindgen": "cross-env-shell \"wasm-bindgen ../../../target/wasm32-unknown-unknown/release/ruffle_web.wasm --target web --out-dir ./pkg --out-name $OUT_NAME\"",
+        "build:wasm-opt": "cross-env-shell \"wasm-opt -o ./pkg/${OUT_NAME}_bg.wasm -O -g ./pkg/${OUT_NAME}_bg.wasm || npm run build:wasm-opt-failed\"",
+
         "build:wasm-opt-failed": "echo 'NOTE: Since wasm-opt could not be found (or it failed), the resulting module might not perform that well, but it should still work.' && echo ; [ \"$CI\" != true ] # > nul",
+
         "build:ts": "tsc -d && node tools/set_version.js",
         "docs": "typedoc",
         "test": "cross-env TS_NODE_COMPILER_OPTIONS={\\\"module\\\":\\\"commonjs\\\"} mocha"
     },
+    "dependencies": {
+        "wasm-feature-detect": "^1.2.11"
+    },
     "devDependencies": {
         "@types/mocha": "^9.0.0",
         "@typescript-eslint/eslint-plugin": "^5.8.1",
diff --git a/web/packages/core/src/load-ruffle.ts b/web/packages/core/src/load-ruffle.ts
index 6367acf36..df10bdab4 100644
--- a/web/packages/core/src/load-ruffle.ts
+++ b/web/packages/core/src/load-ruffle.ts
@@ -2,7 +2,12 @@
  * Conditional ruffle loader
  */
 
-import init, { Ruffle } from "../pkg/ruffle_web";
+import {
+    bulkMemory,
+    simd,
+    saturatedFloatToInt,
+    signExtensions,
+} from "wasm-feature-detect";
 import { setPolyfillsOnLoad } from "./js-polyfills";
 import { publicPath } from "./public-path";
 import { Config } from "./config";
@@ -27,13 +32,40 @@ async function fetchRuffle(config: Config): Promise<typeof Ruffle> {
     // libraries, if needed.
     setPolyfillsOnLoad();
 
+    // NOTE: Keep this list in sync with $RUSTFLAGS in the CI build config!
+    const extensionsSupported: boolean = (
+        await Promise.all([
+            bulkMemory(),
+            simd(),
+            saturatedFloatToInt(),
+            signExtensions(),
+        ])
+    ).every(Boolean);
+
+    if (!extensionsSupported) {
+        console.log(
+            "Some WebAssembly extensions are NOT available, falling back to the vanilla WebAssembly module"
+        );
+    }
+
     __webpack_public_path__ = publicPath(config);
+
+    // Note: The argument passed to import() has to be a simple string literal,
+    // otherwise some bundler will get confused and won't include the module?
+    const { default: init, Ruffle } = await (extensionsSupported
+        ? import("../pkg/ruffle_web-wasm_extensions")
+        : import("../pkg/ruffle_web"));
+
     await init();
 
     return Ruffle;
 }
 
-let lastLoaded: Promise<typeof Ruffle> | null = null;
+type Ruffle =
+    | typeof import("../pkg/ruffle_web")["Ruffle"]
+    | typeof import("../pkg/ruffle_web-wasm_extensions")["Ruffle"];
+
+let lastLoaded: Promise<Ruffle> | null = null;
 
 /**
  * Obtain an instance of `Ruffle`.
@@ -44,7 +76,7 @@ let lastLoaded: Promise<typeof Ruffle> | null = null;
  * @returns A ruffle constructor that may be used to create new Ruffle
  * instances.
  */
-export function loadRuffle(config: Config): Promise<typeof Ruffle> {
+export function loadRuffle(config: Config): Promise<Ruffle> {
     if (lastLoaded == null) {
         lastLoaded = fetchRuffle(config);
     }
diff --git a/web/packages/core/tsconfig.json b/web/packages/core/tsconfig.json
index cf67a8297..07f15fef3 100644
--- a/web/packages/core/tsconfig.json
+++ b/web/packages/core/tsconfig.json
@@ -2,7 +2,7 @@
     "extends": "@tsconfig/recommended/tsconfig.json",
     "compilerOptions": {
         "target": "es2017",
-        "module": "es2015",
+        "module": "es2020",
         "moduleResolution": "node",
         "strict": true,
         "outDir": "pkg",
diff --git a/web/packages/extension/tsconfig.json b/web/packages/extension/tsconfig.json
index ea6ca817f..175cd503b 100644
--- a/web/packages/extension/tsconfig.json
+++ b/web/packages/extension/tsconfig.json
@@ -2,7 +2,7 @@
     "extends": "@tsconfig/recommended/tsconfig.json",
     "compilerOptions": {
         "target": "es2017",
-        "module": "es2015",
+        "module": "es2020",
         "moduleResolution": "node",
         "strict": true,
     },