just as a suggestion, (not knowing what you are importing), split the file up - 11 mil tris in one file sounds way to many, even if you could import it imagine that you would need to ad that file to memory to render it - your 1 gb gpu memory could be insufficient, (notice could - not sure that this would cause you not to be able to import it).
as a short answer to your question, performance isn’t only guided by the amount of polys/verts on a mesh, take a gander @ “Testing and Optimizing Your Content | Unreal Engine 5.2 Documentation” for some good tidbits - there are allot more around the web in non unreal format.
If you want more tips to get this working I would need to know what type of mesh it is.
//hope that helped, glhf