Sorry I meant 1/2 the speed or 2x the time, edited :)

Consider that BLAS written in pure Julia has very decent performance. If you are into numerical computing, you will quickly understand this is crazy.

Carefully written Julia tends to be surprisingly fast. Excessive allocations tend to be a bigger performance problem than raw speed. Of course excessive allocations eventually have an impact on speed as well. There are some idiomatic ways to avoid this.