>>883384What do you mean by professionals? Arborists often use tiny top handle saws that have very minimal power overall.
I work for the USFS in rec but spend time with wildland fire too. The sweet spot are the ~70cc saws. Light enough to hike around with but enough power for almost any tree. Smaller saws can bog in bigger wood and larger saws just don't justify the weight most of the time.
Exceptions abound but I'd guess that most loggers are operating saws in the 70-100cc range as well.
Pic is a of a tree I cut down last week. Really ugly! Saw is a 576xp with a 24" bar.