Why is it that in the late game of a huge map, the program is unresponsive for 10 seconds every time I do any of the following actions: select a citizen for colony ship, select a citizen for constructor ship, citizen for troop transport ship, select new technology, navigate the commands tab?

Processing the AI turns is done within 2 minutes, but I have to wait an additional 2 or more minutes for the "Start a new turn" phase to complete. When it is in that phase the program will not respond or hang until the turn is resolved. I had the same issue with Galactic Civilizations III. Notification prioritization would greatly help with that. There is more, the GUI has a delayed reaction when a button is pressed such as "Build Ship" up to 30 seconds.

The program uses 80 to 97 threads which vary with every save game load.

The program uses less than 10% of my CPU power; a 20 core system with hyper-threading enabled.

up to 12.5 GB of 32 GB RAM is used

up to 6 GB of 16 GB GRAM is used

As far as bugs are concerned I have observed the flowing:

1. Most of the systems have a default name of "Star System"

2. A planet exists with all the tiles set to plains (class 77) but the population cap is limited to 2; housing improvements have no effect

3. the add 2 tiles to core system planets cultural policy has no effect

4. Happiness tied to food supply is nullified after the government is reformed into Federation

5. Some of the technologies have no attributes attached to them

6. Opportunities for cultural points is extremely rare in the late game

I've had that same concern and problem, with no good response or reason for this other than the game is not optimized.  This has always been my concern with the different versions of Galactic Civilization.  They do good in house checking everything over, but they use 'soak' to simulate games to get to mid to late tests, which doesn't seem to really give them the whole impact of what the everyday player sees.  This is why they rely on us the community to provide saved games and examples to them so they can use those examples to make this game great.  It's just hard to troubleshoot the game at that point, once you get to mid/late game to really give that feed back in the current state of the game.  I've also asked that this be addressed so I am able to continue to test the mid/late game.

The first 200-300 turns go by very quickly snap-snap.  Then the game slowly starts to bog down, by the time I get to turn 600, it's a crawl, only getting a handful of turns in a half hour of game play, and that's if I don't have to build anything on a planet (new core world), then it may be only 1 turn in a half hour.  Yet, not capping out my game.  The only thing I can think of is it's maxing out the GPU cores, which is causing the slow down, but I'm barely using any of my 16 core/32 thread system, like you are seeing with your 20 core system.

Shhhh... we like this bug, lol.  Several people have now seen this.

This should get better with more opportunities as they continue to work on the game, after all it's still in Alpha.

When using biomass to add 2 tiles I often find at least one is not visible anywhere.