I have been looking into `StaticArrays.jl`

to speed up linear algebra but I think I am doing something wrong or testing the wrong things.

My first test was a simple linear model:

```
using StaticArrays, Random, BenchmarkTools
Random.seed!(123);
N = 100
p = 10
βtrue = 10 .* rand(p);
_X = rand(N, p);
_y = _X * βtrue + randn(N);
X = SMatrix{N, p}(_X);
y = SVector{N}(_y);
βstore = MVector{p}(zeros(p));
function lm!(X, y, b)
b[:] = X\y
end
@btime lm!(X, y, βstore)
_βstore = zeros(p);
@btime lm!(_X, _y, _βstore)
```

But it looks like the version with regular arrays leads to fewer allocations and is faster:

```
julia> @btime lm!(X, y, βstore);
11.318 μs (87 allocations: 94.55 KiB)
julia> @btime lm!(_X, _y, _βstore);
10.734 μs (85 allocations: 86.52 KiB)
```

So my question is when to use StaticArrays and whether I am doing something wrong here?