You can report this directly to the devs by going into Menu > Feedback. Remember to include the log. I myself have experienced freezing issues in the past, and I can say that the devs certainly know about this if your issue and mine is the same. I've started playing again in the past few days and it has not frozen once for me yet. If you are concerned about losing progress due to this issue, it would be wise to save your simulation every time you make changes.