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.
std::map<CKeyID, int64_t> m_pool_key_to_index;
    std::atomic<uint64_t> m_wallet_flags{0};
    int64_t nTimeFirstKey GUARDED_BY(cs_wallet) = 0;
    /**
     * Private version of AddWatchOnly method which does not accept a
     * timestamp, and which will reset the wallet's nTimeFirstKey value to 1 if
     * the watch key did not previously have a timestamp associated with it.
     * Because this is an inherited virtual method, it is accessible despite
     * being marked private, but it is marked private anyway to encourage use
     * of the other AddWatchOnly which accepts a timestamp and sets
     * nTimeFirstKey more intelligently for more efficient rescans.
     */
    bool AddWatchOnly(const CScript& dest) override EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    bool AddWatchOnlyWithDB(WalletBatch &batch, const CScript& dest) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    bool AddKeyOriginWithDB(WalletBatch& batch, const CPubKey& pubkey, const KeyOriginInfo& info);
    
    bool AddKeyPubKeyWithDB(WalletBatch &batch,const CKey& key, const CPubKey &pubkey) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    bool AddWatchOnlyWithDB(WalletBatch &batch, const CScript& dest, int64_t create_time) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    void AddKeypoolPubkeyWithDB(const CPubKey& pubkey, const bool internal, WalletBatch& batch);
    bool SetAddressBookWithDB(WalletBatch& batch, const CTxDestination& address, const std::string& strName, const std::string& strPurpose);
    
    bool AddCScriptWithDB(WalletBatch& batch, const CScript& script);
    
    interfaces::Chain* m_chain;
    
    WalletLocation m_location;
    
    std::unique_ptr<WalletDatabase> database;