Yeah. There was a change in how the game loads files (due to lags when playing):
There’s also a way to force the game to load everything when it first starts up (which will avoid in-game delays)
Mouse bug - #17 by InterAction_studios
Added loadMode (immediate, opportunistic, on-demand).
Early Access version 35
loadMode is now forced to “immediate” (temporary debugging measure).
Early Access version 36
So yeah. Right now “the most demanding” option is enabled on default which means that at the start your game all files are being loaded to your RAM. We don’t know what IA is checking with that, but weirdly I have much lower RAM usage than it should be.