Example should have performance numbers and comparisons

I'm doing some benchmarking, and while this might be apples to oranges,

1. Invoking quickjs as a wasmtime precompiled using `--eval console.log('hello world')` 1000 times takes approx 7-8s
2. Invoking the hello-world.js embedding in the example 1000 times takes approx 80s or maybe 10x as much time.

```
time for x in `seq 1 1000`; do wasmtime --allow-precompiled quickcheck.cwasm --eval "console.log('hello world')"; done

real 0m7.849s
user 0m3.077s
sys 0m6.752s
```

```
$ time for x in `seq 1 1000`; do ./target/release/wasmtime-test > /dev/null; done

real 1m21.672s
user 0m45.470s
sys 0m38.263s
```

Using `https://gitlab.com/api/v4/projects/47807501/packages/generic/js_interpreters/0.0.1/cweb_quickcheck.wasm` for the example.

It would be good to understand better what performance we can expect and how to benchmark against other options.

檢查 hello-world.js 嵌入範例，並重現 issue 中描述的兩個計時命令，包括與預先編譯的 quickcheck.cwasm 進行比較。判斷哪些測量結果具有可比性，然後記錄預期的效能數據，以及此範例可重現的比較方法。

由索引模型根據 Issue 內容生成。