It took me 1 hour 5 minutes moderate (some would think it's brisk, but the truly brisk passed me) walking to do the reverse - 4s to 4. In J so up front. Included in the 65 minutes was no more than 10 combined pit stop and duty free. Distances in T4 can be very, very long, and I think that accounts for some of the time variance estimations.. The immigration line was not bad, had to wait for a train etc. I'd rather have a longer connection and enjoyed the lounge for a half hour.

That being said, if it wasn't the last flight of the day, I wouldn't avoid it if the choice was a four hour connection.