Adding a single large quad object to scene significantly lowers framerate

I have a level that consists of a long hallway (20 meters wide, 1000 meters long). I want to add a long stretch of carpet down the middle of this. However, Simply adding a single quad (10 meters by 1000 meters) causes my framerate to drop significantly. On my android device, the framerate drops from ~30fps to ~23 fps, just from that single quad.

Even though this is a large object, it seems odd to me that a single 4 vertex rectangle would drop the framerate so much.

Is this expected behavior? How might I solve this problem of putting really long objects into my scene?