Increasing FPS for procedurally added meshes

I’ve reduced the poly count to 20K, but I’m still getting quite poor FPS, like 30-40. I need to add more stuff as well. Also, the meshes I add “flicker”. Here’s a screenshot, there is supposed to be 32 in a square grid, but this shows only half of them (the others flicker in and out).

http://content.screencast.com/users/Andargor/folders/Jing/media/622470c8-a6af-45a4-9bf3-d51e3ca324d7/2014-06-06_1755.png

Any ideas from you rendering gurus?

EDIT: Deleting and reimporting the SkeletalMesh got rid of the flickering. The performance issue remains however.