This is probably the case.I would guess that it doesn't due to the massive block updates it would cause, as well as the immense amounts of dropped entities you would have all of a sudden. Tried in the past getting rid of redwoods very quickly and it was really bad for performance(in some cases caused crashes).
Probably better to just do a bit at the time or to use a Filler or something.
RotaryCraft's bedrock axe gets around that by not taking on the entire tree at once- since v5, I think, it chops down trees (and forests) at about one meter per tick. I haven't tried it on Natura trees yet, but it takes down Twilight Oaks with no trouble or serious lag.