Greater memory footprint due to `keys` and `map`

inspector.factor

: first-column-width ( table model -- width )
    value>> dup sequence? [
        length 1 - 1array
    ] [
        make-mirror keys
    ] if [ unparse-short ] map
    over renderer>> column-titles first suffix
    row-column-widths supremum ;

: <inspector-table> ( model -- table )
    [
        [ make-slot-descriptions ] <arrow> inspector-renderer <table>
            [ invoke-primary-operation ] >>action
            line-color >>column-line-color
            6 >>gap
            15 >>min-rows
            15 >>max-rows
            40 >>min-cols
            40 >>max-cols
            monospace-font >>font
            dup
    ] keep first-column-width 0 2array >>fixed-column-widths ;

The proposed code would not work, because column-titles first returns the string "Key". I'd have to call cell-dim nip + on the string to be able to max it with the result of row-column-widths supremum. But calling cell-dim that way is what I'm trying to avoid by using the row-column-widths in the first place.