nactors* {
    ldy sorted_indices+i ;3
    lax actorY,y         ;4
    sta sort_table,y     ;5
    lda bucket,x         ;4
    sta bucketnext,y     ;5
    tya                  ;2
    sta bucket,x         ;5   total 28*na, assuming last frame's sort indices are in zp
}

nactors * {
    ldy sort_table+i    ; 3
    ldx bucket,y        ; 4
    lda bucket_next,x   ; 4
    sta bucket,y        ; 5
    sta sort_indices+i  ; 3  total 19*na
}