diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 471b821..e4d830a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,25 +25,35 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.sha }}
 
-      - name: Setup node ${{ matrix.node-version }}
-        uses: actions/setup-node@v3
-        with:
-          node-version: ${{ matrix.node-version }}
-
       - name: Install Rust
         uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: nightly
 
+      - name: Cache Rust dependencies
+        uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: "packages/wasm-miniscript"
+          cache-on-failure: true
+
+      - name: Setup node ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+
       - name: Install wasm-pack
         run: |
           rustup component add rustfmt
-          cargo install wasm-pack
+          cargo install wasm-pack --version 0.13.1
+          cargo install wasm-opt --version 0.116.1
 
       - name: Build Info
         run: |
           echo "node $(node --version)"
           echo "npm $(npm --version)"
+          echo "rustc $(rustc --version)"
+          echo "wasm-pack $(wasm-pack --version)"
+          echo "wasm-opt $(wasm-opt --version)"
           git --version
           echo "base ref $GITHUB_BASE_REF"
           echo "head ref $GITHUB_HEAD_REF"
diff --git a/packages/wasm-miniscript/Makefile b/packages/wasm-miniscript/Makefile
index 8653926..412bc41 100644
--- a/packages/wasm-miniscript/Makefile
+++ b/packages/wasm-miniscript/Makefile
@@ -1,4 +1,5 @@
 WASM_PACK = wasm-pack
+WASM_OPT = wasm-opt
 WASM_PACK_FLAGS = --no-pack --weak-refs
 
 ifdef WASM_PACK_DEV
@@ -6,7 +7,12 @@ ifdef WASM_PACK_DEV
 endif
 
 define WASM_PACK_COMMAND
-	$(WASM_PACK) build --out-dir $(1) $(WASM_PACK_FLAGS) --target $(2)
+	$(WASM_PACK) build --no-opt --out-dir $(1) $(WASM_PACK_FLAGS) --target $(2)
+endef
+
+# run wasm-opt separately so we can pass `--enable-bulk-memory`
+define WASM_OPT_COMMAND
+    $(WASM_OPT) --enable-bulk-memory -Oz $(1)/*.wasm -o $(1)/*.wasm
 endef
 
 define REMOVE_GITIGNORE
@@ -22,6 +28,7 @@ endef
 define BUILD
 	rm -rf $(1)
 	$(call WASM_PACK_COMMAND,$(1),$(2))
+	$(call WASM_OPT_COMMAND,$(1))
 	$(call REMOVE_GITIGNORE,$(1))
 	$(call SHOW_WASM_SIZE,$(1))
 endef