`console.log` is slow

Deno is slower than both `node` and `js78` combined. For example
`for.js`:
```js
for (let i = 0; i < 100000; ++i) console.log(`Hello, ${i}`);
```
```sh
$ time node for.js > /dev/null && time deno run for.js > /dev/null && time js78 for.js > /dev/null

real	0m0.342s
user	0m0.309s
sys	0m0.045s

real	0m0.610s
user	0m0.556s
sys	0m0.043s

real	0m0.096s
user	0m0.064s
sys	0m0.031s
```