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.
{
protected:
    CWallet* pwallet;
    int64_t nIndex{-1};
    CPubKey vchPubKey;
    bool fInternal{false};
public:
    explicit CReserveKey(CWallet* pwalletIn)
    {
        pwallet = pwalletIn;
    }
    CReserveKey(const CReserveKey&) = delete;
    CReserveKey& operator=(const CReserveKey&) = delete;
    ~CReserveKey()
    {
        ReturnKey();
    }
    void ReturnKey();
    bool GetReservedKey(CPubKey &pubkey, bool internal = false);
    void KeepKey();
};
class WalletRescanReserver
{
private:
    CWallet* m_wallet;
    bool m_could_reserve;
public:
    explicit WalletRescanReserver(CWallet* w) : m_wallet(w), m_could_reserve(false) {}