Mesh Landscape making FPS drop

Hello everyone! Because of some mechanics in my game, i have to do a landscape with blocks. Unfortunately, when i look for a lot of blocks, my FPS hardly go down. I want to know if have some way to fix this.

My “Engine Scalability By Settings” Qualities is already all low.

PC:
i3-3240 3.40Ghz
8 GB Ram
GT 740 2 GB

In the following photo my FPS was like 5.

Yeah, you are right, that’s about Draw Calls. Merge meshes is not an option for me, cause they need to be separated. How can i use hierarchical instanced stactic meshes?

Actually this fix the FPS problem but my landscape need to be with separated blocks, so i can’t do that. Anyway, thank you!