Minecraft 1.7.10
Forge 10.13.4.1614
TIS-3D-MC1.7.10-1.4.0.78

Casings cause a significant FPS drop when they are in view. In a super flat world, 64 Casings drop FPS from 300 to 100 when I turn towards them. Controllers, having a similar shape, do not have a noticeable effect on FPS. Is it normal that non-working empty Casings create such a load?

This problem is not present in the first versions of the mod for 1.7.10. The latest version without this problem is 0.6.0.40. The first version with this problem is 0.6.1.43.

I'm afraid I don't have the time to support older versions. That said, casings do use a slightly more complex tile/block entity renderer for module rendering, so some overhead is to be expected as opposed to the controller one.