This could be due to a lot of timelines or a lot of tracks, however the value still seems too high. The deep profile view also creates a lot of undesirable bias, so you should again profile without the Deep Profile
option on and see if you still get the same outcome.
You could also try the single asset in the Spine-Unity 3.8-beta runtime, however note that you need to re-export it first.
You could send us your exported asset files to contact@esotericsoftware.com, then we can have a look.