Optimize serializing SharedArrayBuffers for zero values [perf]

lib/serialize/buffers.js

@@ -158,33 +158,32 @@ registerSerializer(ARRAY_BUFFER_TYPE, serializeArrayBuffer);
 function serializeSharedArrayBuffer(record) {
 	const uint = new Uint8Array(record.extra.buf);
 
-	let valNodes,
-		numTrailingZeros = 0,
-		firstNonZeroIndex = 0;
-	uint.forEach((val, index) => {
-		if (val !== 0) {
-			if (!valNodes) {
-				valNodes = [];
-				firstNonZeroIndex = index;
-			}
-			valNodes.push(t.numericLiteral(val));
-			numTrailingZeros = 0;
-		} else if (valNodes) {
-			valNodes.push(null);
-			numTrailingZeros++;
-		}
-	});
-
 	// `new SharedArrayBuffer(8)`
+	const len = uint.length;
 	const node = t.newExpression(
 		this.traceAndSerializeGlobal(SharedArrayBuffer),
-		[t.numericLiteral(uint.length)]
+		[t.numericLiteral(len)]
 	);
 
-	if (valNodes) {
-		// `new Uint8Array(arr).set([1, 2, 3]);`
+	// Set non-zero values (if any)
+	const firstNonZeroIndex = uint.findIndex(byte => byte !== 0);
+	if (firstNonZeroIndex !== -1) {
+		const valNodes = [];
+		let numTrailingZeros = 0;
+		for (let index = firstNonZeroIndex; index < len; index++) {
+			const val = uint[index];
+			if (val === 0) {
+				valNodes.push(null);
+				numTrailingZeros++;
+			} else {
+				valNodes.push(t.numericLiteral(val));
+				numTrailingZeros = 0;
+			}
+		}
+
 		if (numTrailingZeros > 0) valNodes.length -= numTrailingZeros;
 
+		// `new Uint8Array(arr).set([1, 2, 3]);`
 		this.assignmentNodes.push(
 			t.expressionStatement(
 				t.callExpression(