When building more than ~32 buildings on a single planet I can get the game to crash reproducably by simply opening the planet view of the planet in question.
Now, getting enough space to even build that many items requires some terraforming, but once you have done so, starting construction on the items is fine, but as soon as building number 32/33 is actually finished the game will always crash as soon as I try to look at the planet.
I've tried with several custom races as well as the Yor. All show the same pattern.
Extra info: It needs to be unique structures. Filling the entire planet with the same type of structure will not cause a crash.
Ticket: #UUI-806-15054