bitcoin-cli very slow to respond to RPC calls (Raspberry Pi) Running Bitcoin 0.11 on Raspberry Pi 2 (Quad core 900MHz 1GB RAM, 128GB Flash Drive for blockchain, 8GB SD Card for OS and software).

Blockchain is fully synced, 13 connections.
In htop, I see I'm around 700/862MB RAM, 1/99MB Swap. 1 processor is up around 90% but the other 3 are down in the &lt;5% range.

I SSH into the pi (running bitcoind, no GUI) and some commands take forever to get a response. Sometimes getinfo or getpeerinfo will take 30-60 seconds to print out. gettxoutsetinfo takes way longer: almost ten minutes!! I don't see any resources being maxed out in htop during this time.

I know this is a low-power machine, maybe the UTXO set hash in the gettxoutsetingo command is what's specifically taking so long in that case. 

Can I adjust any settings either in the RPi OS or bitcoin.conf to get snappier performance? Ideally I would like to run a few python scripts that use RPC, triggered by bitcoin's blocknotify=...
I have the same set up and getinfo for me takes about 10-20s initially but then takes ~5s there after. (I need to restart the daemon periodically as it crashes for some reason). I'm running 0.11.1 and haven't made any special tweaks. gettxoutsetinfo takes around 12 minutes. CPU, RAM and Swap comparable with what you have as well. 

Hardware is probably the most obvious limitation. You could overclock the Pi CPU but I doubt it will drastically reduce the response time though.