Heap allocated struct faster than comptime calculated arrays

Explain
1

I did a small experiment:
My chessprogram computes all attackdata @comptime into hard constant arrays, so these are baked into the exe.
Now I did a clone which creates these into a heap-created struct with attackdata @runtime.
To my surprise the heap-version is faster.
Why could that be?

Bench:

Total nodes: 18999768562 13.772s 1379.5293 Mnodes/s (1379529270) // comptimes
Total nodes: 18999768562 13.089s 1451.5786 Mnodes/s (1451578573) // heap

const Data = struct {
    file_magics: [64]MagicEntry,
    main_magics: [64]MagicEntry,
    anti_magics: [64]MagicEntry,
    pawn_attacks_white: [64]u64,
    pawn_attacks_black: [64]u64,
    knight_attacks: [64]u64,
    king_attacks: [64]u64,
    rank_attacks: [64 * 64]u64,
    file_attacks: [64 * 64]u64,
    diag_main_attacks: [64 * 64]u64,
    diag_anti_attacks: [64 * 64]u64,
};

const MagicEntry = struct {
    mask: u64,
    magic: u64,
};
2

Maybe having them in a struct rather than global arrays, the compiler was able to rearrange the struct and get better locality of reference for the pattern of memory access.

Try doing deeper profiling and look at cache misses.