RPC Calls are very slow to respond

The wallet rpc calls are very slow to respond

This takes 12 seconds to get executed
```
./lbrycrd-cli -getinfo
{
"version": 170302,
"protocolversion": 70015,
"walletversion": 169900,
"balance": 0.00000000,
"blocks": 750800,
"timeoffset": 0,
"connections": 8,
"proxy": "",
"difficulty": 455175102026.4689,
"testnet": false,
"keypoololdest": 1557683735,
"keypoolsize": 1000,
"paytxfee": 0.00000000,
"relayfee": 0.00001000,
"warnings": ""
}
```

The wallet is almost always using 100% of a CPU core.
Running v17.3.2

Start by reproducing the reported delay with `./lbrycrd-cli -getinfo` on v17.3.2 while observing CPU usage. No source file or test is named, so trace the RPC and wallet execution paths to identify the cause. Done means wallet RPC calls respond promptly without a core remaining at 100% CPU.

Written by the indexing model from the issue text.