Assuming you knew C and CPU arch terms like SIMD at age 6, imagine an array of complex structs compared to an int[]. The latter can be read directly from disk a

Assuming you knew C and CPU arch terms like SIMD at age 6, imagine an array of complex structs compared to an int[]. The latter can be read directly from disk and aggregated (ie summed) very fast via SIMD instructions. Whereas a dynamically sized structure for rows (like how traditional databases store them) requires a lot of branch and dereference logic.