The lag is VERY real, but I'm sure is combination of bots/DDoS/Heavy usage during major sells.  That said I was VERY miffed yesterday on a margin trade.  I had over 60% margin on a Factom sell RIGHT before a big drop.  Walked away for 10 minutes, came back and it had auto-closed with no explanation or message literally seconds before the drop where I would've made a killing.

My only guess that makes sense is there was a brief (very very short) mega-pump seconds before the drop, which would only occur or be coordinated for the purposes of shedding margin traders who didn't have a MASSIVE reserve in their margins.  There's no other technical reason I can see for it to have closed outside of technical malfunction/malfeasance.

Definitely wasn't make or break, but I've certainly been transitioning most of my assets out of Polo because of this and some other oddness I've seen there for the last month+.

They can't be beat for liquidity, but I can't imagine they're not complicit to some extent in market manipulation.