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.
{
    CKeyMetadata meta;
    {
        LOCK(cs_wallet);
        auto it = mapKeyMetadata.find(keyID);
        if (it != mapKeyMetadata.end()) {
            meta = it->second;
        }
    }
    if (meta.has_key_origin) {
        std::copy(meta.key_origin.fingerprint, meta.key_origin.fingerprint + 4, info.fingerprint);
        info.path = meta.key_origin.path;
    } else { 
        std::copy(keyID.begin(), keyID.begin() + 4, info.fingerprint);
    }
    return true;
}
bool CWallet::AddKeyOriginWithDB(WalletBatch& batch, const CPubKey& pubkey, const KeyOriginInfo& info)
{
    LOCK(cs_wallet);
    std::copy(info.fingerprint, info.fingerprint + 4, mapKeyMetadata[pubkey.GetID()].key_origin.fingerprint);
    mapKeyMetadata[pubkey.GetID()].key_origin.path = info.path;
    mapKeyMetadata[pubkey.GetID()].has_key_origin = true;
    mapKeyMetadata[pubkey.GetID()].hdKeypath = WriteHDKeypath(info.path);
    return batch.WriteKeyMetadata(mapKeyMetadata[pubkey.GetID()], pubkey, true);
}