Benchmark proxy (#3109)

packages/beacon-state-transition/test/perf/misc/proxy.test.ts

@@ -0,0 +1,46 @@
+import {itBench} from "@dapplion/benchmark";
+import {expect} from "chai";
+
+describe("Proxy cost", () => {
+  const n = 100_000;
+  const array: number[] = [];
+  for (let i = 0; i < n; i++) {
+    array.push(i);
+  }
+
+  const arrayWithProxy = new Proxy(array, {
+    get(target, p) {
+      if (p === "length") {
+        return target.length;
+      } else {
+        return target[(p as unknown) as number];
+      }
+    },
+  });
+
+  const wrappedArray = {
+    array,
+    get(i: number) {
+      return this.array[i];
+    },
+  };
+
+  it("Check is correct", () => {
+    for (const i of [0, 1, Math.floor(n / 2)]) {
+      expect(array[i]).to.equal(i, `Wrong value array[${i}]`);
+      expect(arrayWithProxy[i]).to.equal(i, `Wrong value arrayWithProxy[${i}]`);
+    }
+  });
+
+  itBench(`regular array get ${n} times`, () => {
+    for (let i = 0; i < n; i++) array[i];
+  });
+
+  itBench(`wrappedArray get ${n} times`, () => {
+    for (let i = 0; i < n; i++) wrappedArray.get(i);
+  });
+
+  itBench(`arrayWithProxy get ${n} times`, () => {
+    for (let i = 0; i < n; i++) arrayWithProxy[i];
+  });
+});