This section alludes to it although maybe we should say it more explicitly.
https://docs.julialang.org/en/v1/manual/performance-tips/#man-performance-abstract-container
julia> [1 1.0 "sfsdf"]
1×3 Array{Any,2}:
1 1.0 "sfsdf"
julia> typeof(ans)
Array{Any,2}
julia> (1, 1.0, "sfsdf")
(1, 1.0, "sfsdf")
julia> typeof(ans)
Tuple{Int64,Float64,String}
An array of Any is abstract and is hard for the compiler to write optimized code for. See @stevengj 's lecture to understand the problem there:
