Just for example i created a mesh using the loft object in C4D.
[SPOILER]
(note that the object information in C4D is still counting quads and the caps as ngons)
If this shape is exported as loft object, it will have about 4522 triangles in UE4.
Also the inside cap will be invisible due to reversed normals and backface culling.
If it’s at least converted to a polygon object, caps connected, optimized and normals aligned,
you get a total of 3034 triangles.
Now if you take it one step further and delete all the unneccessary edeloops,
you can bring this mesh down to 1422 triangles.
This is less then 1/3 of the polycount of the unoptimized loft object export and only half of the slightly optimized one.