Kerbal Space Program

I've put these two issues together as I believe one causes the other.

When first starting the game it uses around 4 GB of RAM, which is reasonable. However, after playing for a while the game takes longer and longer to switch between scenes. I noticed that the memory slowly balloons. At one point it hit 11 GB on my system before I noticed that the system was starting to swap (which made the game unplayable).

Closing the game and opening it again reduces its usage back to 4 GB, for the ballooning to start all over again.

I'm new to the game so have no mods, but the game came with the expansions included. I also do not know if this is new to 1.8.0 as I only had the game for a day or so before it was updated (automatically via Steam), which also kicked me out mid-game.

There are other bug reports regarding memory leaks but they seem to be specific, and sadly I cannot be. But if there are multiple sources of leaks then this would explain the issue.
https://bugs.kerbalspaceprogram.com/issues/23687
https://bugs.kerbalspaceprogram.com/issues/20770
https://bugs.kerbalspaceprogram.com/issues/15054

I have Windows 10 if testing with that would be any help, but I tend to stick with Ubuntu 18.04.