difficulty up 250% was just 72K yesterday. 
Anyone know why? Some prospectors grabbing a bunch of coins in case this goes big in future, getting in while there's still a large number of coins at low difficulty thanks to still relatively small number of miners?
Someone probably bought a chunk of NiceHash hashing power and pointed it this way. So the jump in difficulty should be temporary, or at least intermittent. This is probably not a terrible thing as it means someone thinks BitcoinZ is worth investing in.
Maybe this is the culprit? https://imgur.com/a/i2yVt Look how much he mined today and how many are still being verified!