It takes from 5 (shortest) to almost 40 (longest) minutes for `bitcoin-cli gettxoutsetinfo` to return an _empty_ dict. I noticed this first whilst configuring the Statoshi branch of Bitcoin Core, but went back to install Bitcoin Core (git clone -b v0.11.2 https://github.com/bitcoin/bitcoin.git) to find the same results.

```
20:10 pi@raspinode:~/bin/bitcoin.orig $ bitcoin-cli gettxoutsetinfo
{
}
20:12 pi@raspinode:~/bin/bitcoin.orig $ bitcoin-cli getinfo
{
    "version" : 110200,
    "protocolversion" : 70002,
    "blocks" : 393193,
    "timeoffset" : 0,
    "connections" : 12,
    "proxy" : "",
    "difficulty" : 113354299801.47113037,
    "testnet" : false,
    "relayfee" : 0.00005000,
    "errors" : ""
}
20:17 pi@raspinode:~/bin/bitcoin.orig $
```

Raspberry Pi 2 - 1GB memory - 4 core CPU 900MHz - Blockchain on SanDisk Ultra Android microSDXC 128GB up to 80 MB/Sec Class 10

All other RPC calls through bitcoin-cli are answered promptly and correctly.
See also issue on jlopp/statoshi https://github.com/jlopp/statoshi/issues/19#issuecomment-171350739

{
    UniValue rv(UniValue::VOBJ);
    bool activated = false;
    switch(version)
    {
        case 2:
            activated = pindex->nHeight >= consensusParams.BIP34Height;
            break;
        case 3:
            activated = pindex->nHeight >= consensusParams.BIP66Height;
            break;
        case 4:
            activated = pindex->nHeight >= consensusParams.BIP65Height;
            break;
    }
    rv.push_back(Pair("status", activated));
    return rv;
}
static UniValue SoftForkDesc(const std::string &name, int version, CBlockIndex* pindex, const Consensus::Params& consensusParams)