looks for me like you want to transpose a matrix with headlines (aka table) to get hashes of columns.

just for fun a solution with List::MoreUtils :

(though I doubt it's faster...as long you are not slurping a text table =)

  DB<201> \@tab
 => [
  ["A", "B", "C", "D"],
  ["a1", "b1", "c1", "d1"],
  ["a2", "b2", "c2", "d2"],
  ["a3", "b3", "c3", "d3"],
]

  DB<202> @head= @{$tab[0]}
 => ("A", "B", "C", "D")

  DB<203> use List::MoreUtils qw/part/

  DB<204> $i=-1; %col=(); 

  DB<205> @col{@head} = part {$i++; $i %= @head } map {@$_} @tab[1..3]
+ 
 => (
  ["a1", "a2", "a3"],
  ["b1", "b2", "b3"],
  ["c1", "c2", "c3"],
  ["d1", "d2", "d3"],
)

  DB<206> \%col
 => {
  A => ["a1", "a2", "a3"],
  B => ["b1", "b2", "b3"],
  C => ["c1", "c2", "c3"],
  D => ["d1", "d2", "d3"],
}
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