Data is ∘.(2(?⍴)⍨,)⍨ ⌈1.6*⍳16 for Dyalog 15.0 and ∘.(2(?⍴)⍨(⌈1e5÷×),,)⍨ ⌈1.6*⍳16 for 16.0. CPU: Intel Kaby Lake i7-7500U.
∘.(2(?⍴)⍨,)⍨ ⌈1.6*⍳16
∘.(2(?⍴)⍨(⌈1e5÷×),,)⍨ ⌈1.6*⍳16