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.
"\nAs a JSON-RPC call\n"
            + HelpExampleRpc("importprivkey", "\"mykey\", \"testing\", false")
                },
            }.ToString());
    if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Cannot import private keys to a wallet with private keys disabled");
    }
    WalletRescanReserver reserver(pwallet);
    bool fRescan = true;
    {
        auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        EnsureWalletIsUnlocked(pwallet);
        std::string strSecret = request.params[0].get_str();
        std::string strLabel = "";
        if (!request.params[1].isNull())
            strLabel = request.params[1].get_str();
        
        if (!request.params[2].isNull())
            fRescan = request.params[2].get_bool();
        if (fRescan && pwallet->chain().getPruneMode()) {
            throw JSONRPCError(RPC_WALLET_ERROR, "Rescan is disabled in pruned mode");
        }
        if (fRescan && !reserver.reserve()) {
            throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
        }
        CKey key = DecodeSecret(strSecret);
        if (!key.IsValid()) throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid private key encoding");
        CPubKey pubkey = key.GetPubKey();
        assert(key.VerifyPubKey(pubkey));