4.0 and Biogenesis brought features or the groundwork for future features that have been at the top of the list of requested items for Stellaris since 2.2 dropped and caused a ramp up of lag that eventually ends most games(late game lag, internal politics, growth(3.0 ceiling and 2 free Pops and Growth slots per Colony)); the fact all these new things came together wrong is most likely due to half the changes being made by the Custodian team that usually fixes and fits the changes made by other teams, so there wasn't anyone else to do it and it released at the same time as the DLC.
I think it's time to consider doing what Creative Assembly does, and separate the big changes into their own update slot in the yearly schedule and use that for the bulk of Free-Loadable-Content(FLC) features for the year at the same time as major Custodial changes. Instead of right now where for the last two years we've had a fast cadence of 3 DLC a year, this year they tagged a whole DLC into one of those slots and took the implementation and integration(Custodian) team and gave them a FLC to work on and release simultaneaously. We went from 3 DLC with sufficient Custodial time last year(and there were still troubles) to a DLC and a FLC with no Custodial time and 2 more DLC coming up with still a lot to do on the first two before we get there.
Just separate the big rework changes to be at the same time as a FLC launch: you get to advertise a free giveaway(that you have been doing already for 9 years in smaller pieces), the FLC takes all this review heat but none of the pricing heat, your Custodian team can do their job instead of being extra Devs, and you can either put it at the begining of the year and have the rest to fix and fit it's reworks into the greater game, or put it at the end and work towards it, with the same 3 DLC getting their own space, time, and attention to bring them up to par before the next update.
There has been clamour for reform for late game lag, Pop Growth(3.0 was a bandaid solution to the lag but used gamey solutions), Bioships, and internal Politics for as long as I can remember, and the Planet and economy changes seem like much more of a natural progression from the 2.2 economic system than that was from 1.x in my opinion. The new Pop groups seem ripe for future interaction with Factions, Ethic troubles, and internal Politics as well. It's just extremely unfortunate and probably preventable that they decided to do it all at once and have the Custodians build it and never get the time after to take a step back and do what they have done a great job of doing: all those wonderful things everyone keeps bringing up about the 3.14 systems were almost all the result of the Custodian initiative getting to work on them since 2021, so taking them off their old job to add even more custodial work to the pile, dropping two big piles, and not allocating the necessary time after it seems obvious we would have the same issues we had back when we had no Custodial team, since we didn't.
I strongly believe we would not be facing half the issues right now if 4.0 and Biogenesis has been separated; we even had two DLC within a month in spring 2023 with First Contact and Paragons, and the issues weren't compounding this much from what I remember. The Leader rework isn't my favourite but I seem to remember that and the First Contact and Intel reworks being mostly functional.
