OK, three times is not a charm. Immense custom spiral galaxy with common/common/common downloaded off of steam with 5 custom races made with the designer so no cheating. 1.8 with all DLC and add-ons including terrans, 32 GB RAM, 6 core Intel chip, EVGA 980TI, game and OS loaded on Samsung EVO's 850 so hardware should be OK. Game crashed around turn 230, first it slows to a crawl then goes black screen and need to go to task manager to exit. I played it through with 1.71 so it is definitely something introduced with 1.8.
Edit: Did a verify game cache, came back with 3 files corrupted. was able to resume the game and play for about 20 turns. Game displayed same behavior so did the verify again, 1 file corrupted. Restart and game plays for a couple turns and displays behavior. Somehow some files get corrupted as the play goes on.