In both of my playthroughs I have experienced Time freezing in the late game. It usually lasts around 10-15 seconds and is very annoying. During the freezing I can still move around in the game and click on things, the sound still works, however I cannot give fleets orders, build anything, change the speed or pause the game. I play on fastest speed usually but I have experienced this on fast and normal.
Here is my dxdiag and save game.
Here is my dxdiag and save game.