In-place mul! much slower than * for real-complex matrix multiplication

[photor]

This issue has been discussed in this topic:

In-place multiplication is too much slower for ComplexF64

The ordinary version: using BenchmarkTools const p = 60 const dd=randn(p,p) const ψ=randn(p,p*p)+im*randn(p,p*p) function d2x(ψ::Array{ComplexF64,2})::Array{ComplexF64,2} ψr=dd*ψ return ψr end @btime d2x(ψ); The result is 1.330 ms (4 allocations: 3.35 MiB) The in-place version: function d2x(ψ::Array{ComplexF64,2})::Array{ComplexF64,2} ψr = similar(ψ) mul!(ψr,dd,ψ) return ψr end @btime d2x(ψ); The result is 9.511 ms (8 allocations: 3.30 MiB) Is it a bug or somethin…