Using my S7 Edge, both DJI and Litchi have always been perfect on video transmission.  Took th latest FW update yesterday and now DJI GO is essentially useless with a 4-5 second lag on live view. Litchi is unaffected..   Anyone else have this happen or can recommend anything for me to try to fix it?

What version of the app are you using?  If not the latest, you may try that to see if it helps.

Try clearing the phone app cache, then check phone memory to make sure its not full.

I am running 3.1.8.   I cleared the cache, and restarted the phone and same thing.  DJI is laggy, Litchi seems to be OK.   Not sure what else to look at.  Maybe roll back to an earlier version of the app?

My suggestion won't fix the Go app issue but will allow you to have pretty uneventful flights: use Litchi. DJI have been distributing buggy FW updates and Go app update for too long. Amazingly very few issues with Litchi, so why can't DJI get it (almost) right as well?

is it that good, i was considering that purchase to Litchi myself because the go app blows

I've had essentially the same issue since I refreshed my FW (for no good reason). I think the refresh somehow made a change and my previously flawless connection through OTG is now too laggy to use. However, if I connect through WiFi the lag is gone, but the connection reliability is down.