Performing the following (note the range of 10,000):

`importmulti '[{"desc": "sh(wpkh([aeee1e6a/49h/1h/0h]tpubDC5bVdaveQYxGFztMShFAjU637kKjrs9FD8ne1oHR7z8tLeQJExsaxWRVeSpcCcYMdp5ecf2LQhuVaeYFZ7YEpvWTJr4nDGUJrmuvLuTSsp/1/*))", "keypool": true, "timestamp": "now", "watchonly": true, "internal": true, "range": {"end": 1000}}]' '{"rescan": false}'`

takes many minutes. @achow101 reports a similar import taking 6 minutes on his machine.
{
    if (IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
        return false;
    }
    {
        LOCK(cs_wallet);
        WalletBatch batch(*database);
        for (const int64_t nIndex : setInternalKeyPool) {
            batch.ErasePool(nIndex);
        }
        setInternalKeyPool.clear();
        for (const int64_t nIndex : setExternalKeyPool) {
            batch.ErasePool(nIndex);
        }
        setExternalKeyPool.clear();
        for (const int64_t nIndex : set_pre_split_keypool) {
            batch.ErasePool(nIndex);
        }
        set_pre_split_keypool.clear();
        m_pool_key_to_index.clear();
        if (!TopUpKeyPool()) {
            return false;
        }
        WalletLogPrintf("CWallet::NewKeyPool rewrote keypool\n");
    }
    return true;
}
size_t CWallet::KeypoolCountExternalKeys()