First of all, I wanna say "thanks" to all developers, Distant Worlds 2 is the most exciting and deep 4x strategy that I've ever played.
I was always playing on big maps (the smallest one was 750 stars, I think) and a year ago the game at the late stages wasn't playable even on my system (Intel i7 13700, 128GB DDR5, Nvidia RTX 4080, SSD), now it is, so this the additional respect for the developers.
Now, the issues and thoughts:
1. Invasion fleets behavior is still weird. Most probably it's due to the performance issues, but for me it's a common situation that during the invasion some troop ships arrive on the target planet and wait for the rest of the ships or other fleets. If the planet has defense systems (in orbit or land), my troop carriers get destroyed while waiting. It's frustrating.
2. Another thing that I found out recently, is that there's a bombing possibility during the invasion. It reduces the population, destroys facilities (including ancient ruins), and damages the planet (and probably affects reputation), but sometimes (for capitals usually) it's a needed thing due to the huge ground armies. However, I can do this only manually. Would be great to have some AI settings related to this.
3. And final issue with invasion fleets - they load troops randomly and very slow regardless of the Garrison settings of the AI. Even if I have a huge empire with 100+ colonies and huge armies and about 10 fleets, 2-3 of them will be 75-90% full, most of them 25-50%, and a couple will be completely empty.
4. Research screen performance on the late game is very poor (even for just scrolling while the game is paused), and I can't understand why. It seems to be related to the size of the empire, maybe a resources-searching algorithm for project funding?
5. Would be great to have the possibility to re-order the queue for research using drag'n'drop feature. I usually have 6 concurrent projects, 1 of them dedicated to the warp techs, 1 for new ships, 1 for diplomacy, 1 for colonization, and the rest 2 for other things. If I have some warp research finished and I'd like to put a next one, I have to add it at the bottom of the queue and click a lot to move it up.
6. With the same logic, would be great to force AI to speed up all research projects. In the mid-game I face the situation when warp or colonization researches are huge (up to 20 years instead of weapons, which usually 6-12 months), but I have free money to speed up them, and AI doesn't do this, so I have to do it manually again.
7. In the late game AI doesn't usually queue new projects, but it seems like a performance issue. It does, but rarely.
8. I think it would be great to increase the size and cost of "repeatable" research projects, maybe 1.5x or 2x, or even 3x each time it's researched. Because enemy AI uses it too, and very soon they "abuse" just one weapon tech to be ultimate. Also it makes sense, that the further you improve something, the more effort it takes.
9. Would be great to have separate diplomacy settings for independent colonies. I usually manually switch all colonies from "invasion" to "diplomacy" (because invading affects reputation a lot, and considering issues 1-3, it's just easier and faster this way), and I'd like AI to automatically offer gifts and sign treaties with the independent colonies, but not other empires.
10. When I have all galaxy being explored, the AI still builds exploration ships that are idle, even if I manually retire them. Would be great to fix this (but there are some priority settings, that I might misunderstood and just need to adjust).
11. Sometimes when I completely destroy another empire, it appears on the diplomacy screen after a short period of time, with no colonies or bases or fleet, but with some research points. I don't see it in the game editor and so, not able to switch to play as this empire, to check what's left. Not a very important bug, but little bit annoying.
12. Messages, but I saw plans to redo this part

Thanks for reading this. Again, the game rating, according to me, is 12/10 and I'm really enjoying it and looking forward to new updates.