It wasn't too long but there were a lot of unique issues.

We left late out of EWR because Germany still had a mask mandate and some folks freaked out and had to be removed.

There was a medical emergency on the flight, so we parked at a remote stand and had to wait for the paramedics to remove the person. But there was an issue with the stairs, so we had to wait for a 'lift' to be brought over to take the person off, who ended up walking off on her own power and throwing her luggage at the paramedics. (Lots of drama).

Anyway, we got in 3 hours late. Since we were bussed in, there was no advantage to being in business class as everyone arrived at the same time. So even being in the back of the line, it was quick through passport control. Maybe 15 minutes max? Instead of fussing with united customer service, I just went to the nearest lounge and got rebooked. I then walked and followed signs (the best way to navigate FRA). I went to an elevator, went down, walked a corridor, went up, then I was in another terminal and followed the signs to the gate, which led me to a passport check which was very quick.

So, if all the other drama hadn't happened, I would say it was maybe 30-45 minutes if I didn't stop in the first lounge?

United will probably always land at that terminal, but the EDI flight might be in the same area or might be in another terminal, so you might or might not have to do all that. Either way, it was not a huge deal. Just funny to spend 30 minutes in the EU.