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.
fRescan = options["rescan"].get_bool();
        }
    }
    WalletRescanReserver reserver(pwallet);
    if (fRescan && !reserver.reserve()) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
    }
    int64_t now = 0;
    bool fRunScan = false;
    int64_t nLowestTimestamp = 0;
    UniValue response(UniValue::VARR);
    {
        auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        EnsureWalletIsUnlocked(pwallet);
        
        const Optional<int> tip_height = locked_chain->getHeight();
        now = tip_height ? locked_chain->getBlockMedianTimePast(*tip_height) : 0;
        for (const UniValue& data : requests.getValues()) {
            GetImportTimestamp(data, now);
        }
        const int64_t minimumTimestamp = 1;
        if (fRescan && tip_height) {
            nLowestTimestamp = locked_chain->getBlockTime(*tip_height);
        } else {
            fRescan = false;
        }
        for (const UniValue& data : requests.getValues()) {
            const int64_t timestamp = std::max(GetImportTimestamp(data, now), minimumTimestamp);
            const UniValue result = ProcessImport(pwallet, data, timestamp);