1:57 in a pug... killing shiro was only about 30 seconds though, after everyone had talked to kuunavang and slowly walked across the bridge we had wasted a lot of time.
If you all took a running skill you could easily do it under a minute
I managed to get about 1:06, after we had a perfect team and spammed the special skills, but unfortunately I didn't get a shot since the folder was full.