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.
throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
    }
    int64_t nTimeBegin = 0;
    bool fGood = true;
    {
        auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        EnsureWalletIsUnlocked(pwallet);
        fsbridge::ifstream file;
        file.open(request.params[0].get_str(), std::ios::in | std::ios::ate);
        if (!file.is_open()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot open wallet dump file");
        }
        Optional<int> tip_height = locked_chain->getHeight();
        nTimeBegin = tip_height ? locked_chain->getBlockTime(*tip_height) : 0;
        int64_t nFilesize = std::max((int64_t)1, (int64_t)file.tellg());
        file.seekg(0, file.beg);
        
        
        pwallet->chain().showProgress(strprintf("%s " + _("Importing..."), pwallet->GetDisplayName()), 0, false); 
        std::vector<std::tuple<CKey, int64_t, bool, std::string>> keys;
        std::vector<std::pair<CScript, int64_t>> scripts;
        while (file.good()) {
            pwallet->chain().showProgress("", std::max(1, std::min(50, (int)(((double)file.tellg() / (double)nFilesize) * 100))), false);
            std::string line;
            std::getline(file, line);
            if (line.empty() || line[0] == '#')
                continue;
            std::vector<std::string> vstr;
            boost::split(vstr, line, boost::is_any_of(" "));