The weight of the animation increases after import

Hey. I have a file with animation in fbx format. With a mesh, it weighs 16, without - 6. I did it in a Blender.
After importing into UE4 4.19.2, the animation size increases to 600 mb. I’m new and I can not understand what the problem may be. All my other riggs and animations have this problem.
Animations that I downloaded such a problem do not have, only those that I myself made in Blender.