Game stuck at Turn 423 (not the first time)

Hi

My game is stuck and hanging on AI enemy turn. This has happened multiple times. Each time I go back a few saves and try and continue but now it is hanging too frequently.

This seems to be something that has been in the game since its launch as i have faced this quite a few times on different machines.  

Is there not a way to bypass the hanging as hours are spent playing a game that then cannot be completed.

Thanks