"Fast subwoofer"? Did you ever hear a fast 30 foot organ pipe? The instruments which generate the frequencies that the subwoofer handles are by their nature "slow".
A bass drum you say? Well, the leading edge of its sound may be steep, but that will be rejected by the subwoofer crossover, and routed to the woofer or midrange driver.
A bass drum you say? Well, the leading edge of its sound may be steep, but that will be rejected by the subwoofer crossover, and routed to the woofer or midrange driver.