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 (fRescan && !reserver.reserve()) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
    }
    if (!IsHex(request.params[0].get_str()))
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey must be a hex string");
    std::vector<unsigned char> data(ParseHex(request.params[0].get_str()));
    CPubKey pubKey(data.begin(), data.end());
    if (!pubKey.IsFullyValid())
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey is not a valid public key");
    {
        auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        for (const auto& dest : GetAllDestinationsForKey(pubKey)) {
            ImportAddress(pwallet, dest, strLabel);
        }
        ImportScript(pwallet, GetScriptForRawPubKey(pubKey), strLabel, false);
        pwallet->LearnAllRelatedScripts(pubKey);
    }
    if (fRescan)
    {
        RescanWallet(*pwallet, reserver);
        {
            auto locked_chain = pwallet->chain().lock();
            LOCK(pwallet->cs_wallet);
            pwallet->ReacceptWalletTransactions(*locked_chain);
        }
    }
    return NullUniValue;
}
UniValue importwallet(const JSONRPCRequest& request)