It seems the onion site is down, I'm using this for a long time and have never seen this happen, is there any way to know their news or updates like on twitter or something?
It's down for me as well, but I think they are updating something, if you didn't know Tor has been under heavy attacks in last few days, so I think this might be the reason for Chipmixer downtime.
Anything related with Tor was loading slow for me in this time, and this was probably a Tot security issue bug that was fixed in latest version 0.4.7.8:
https://gitweb.torproject.org/tor.git/plain/ChangeLog