Re: [julia-users] Immutable vs. Mutable composite types: Trying to understand performance and memory allocations

[Kristoffer Carlsson]

The reason you get allocations is because you are running things in global 
scope. 

http://docs.julialang.org/en/release-0.4/manual/performance-tips/#avoid-global-variables

Seems immutable would work well for your use case.