Why is static batching causing so much lag?

I have a scene with a large number of objects which are all static. Since Unity 4.3, when I build and run the game, it runs extremely slowly while if I run it in the Unity editor (even in game mode) it runs fine. I’ve noticed that the frame rate increases almost 100% if I disable static batching, however it still runs slower than it did before Unity 4.3.

Any idea what’s going on?

Known problem with 4.3

For now, just stick with 4.2.