diff --git a/package-lock.json b/package-lock.json
index 6c28814..0b17289 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -592,9 +592,9 @@
       }
     },
     "ffjavascript": {
-      "version": "0.0.4",
-      "resolved": "https://registry.npmjs.org/ffjavascript/-/ffjavascript-0.0.4.tgz",
-      "integrity": "sha512-6eiRvy+YuGCRjH4U8KdJbRel5VBW0zeuUL1FXQ+fFxTp5xv2ClqTfCYf5ClUtq0voGpd9XJAdUCvgIxHDbAQ0Q==",
+      "version": "0.0.5",
+      "resolved": "https://registry.npmjs.org/ffjavascript/-/ffjavascript-0.0.5.tgz",
+      "integrity": "sha512-7je6PydOWLDUj3vU8JeCUgeezg4yrG/6qjlukQNuPHeeavnM4REcrN9LA2+xtqIMIPdx/wdUkPMQpixsz+CdIw==",
       "requires": {
         "big-integer": "^1.6.48"
       }
diff --git a/package.json b/package.json
index ee8c5b8..11c02bb 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,7 @@
     "chai": "^4.2.0",
     "circom_runtime": "0.0.3",
     "ffiasm": "0.0.2",
-    "ffjavascript": "0.0.4",
+    "ffjavascript": "0.0.5",
     "ffwasm": "0.0.6",
     "fnv-plus": "^1.3.1",
     "r1csfile": "0.0.3",
diff --git a/ports/wasm/builder.js b/ports/wasm/builder.js
index f96bd10..c770813 100644
--- a/ports/wasm/builder.js
+++ b/ports/wasm/builder.js
@@ -923,41 +923,41 @@ class BuilderWasm {
     }
 
     _buildComponents(module) {
-        const bytes = [];
+        const bytes = new Array(this.components.length*5*4);
+        bytes.length=0;
         for (let i=0; i<this.components.length; i++) {
             const c = this.components[i];
 
-            bytes.push(intToBytes32(this.hashMaps[c.hashMapName].pointer));
-            bytes.push(intToBytes32(this.componentEntriesTables[c.entryTableName].pointer));
-            bytes.push(intToBytes32(i));
-            bytes.push(intToBytes32(c.nInSignals));
-            bytes.push(intToBytes32(c.newThread ? 1 : 0));
+            bytes.push(...intToBytes32(this.hashMaps[c.hashMapName].pointer));
+            bytes.push(...intToBytes32(this.componentEntriesTables[c.entryTableName].pointer));
+            bytes.push(...intToBytes32(i));
+            bytes.push(...intToBytes32(c.nInSignals));
+            bytes.push(...intToBytes32(c.newThread ? 1 : 0));
 
             module.addFunctionToTable(c.functionName);
         }
 
-        const fBytes = [].concat(...bytes);
-        this.pComponents = module.alloc(fBytes);
+        this.pComponents = module.alloc(bytes);
     }
 
     _buildMapIsInput(module) {
-        const bytes = [];
+        const bytes = new Array(this.mapIsInput.length*4);
+        bytes.length=0;
         for (let i=0; i<this.mapIsInput.length; i++) {
-            bytes.push(intToBytes32(this.mapIsInput[i]));
+            bytes.push(...intToBytes32(this.mapIsInput[i]));
         }
 
-        const fBytes = [].concat(...bytes);
-        this.pMapIsInput = module.alloc(fBytes);
+        this.pMapIsInput = module.alloc(bytes);
     }
 
     _buildWit2Sig(module) {
-        const bytes = [];
+        const bytes = new Array(this.wit2sig.length*4);
+        bytes.length =0;
         for (let i=0; i<this.wit2sig.length; i++) {
-            bytes.push(intToBytes32(this.wit2sig[i]));
+            bytes.push(...intToBytes32(this.wit2sig[i]));
         }
 
-        const fBytes = [].concat(...bytes);
-        this.pWit2sig = module.alloc(fBytes);
+        this.pWit2sig = module.alloc(bytes);
     }
 
     _buildCircuitVar(module) {