I'm looking to allocate a vector of small-sized structs.

This takes 30 milliseconds and increases linearly:

```
let v = vec![[0, 0, 0, 0]; 1024 * 1024];

```

This takes tens of microseconds:

```
let v = vec![0; 1024 * 1024];

```

Is there a more efficient solution to the first case? I'm okay with unsafe code.