Game lags after entering any building and requires a restart

[sewer-dweller]

When in the outside world the game runs smoothly, but once I enter any building (such as Kolhola, the O Mart, Greenhouse, Deekula A) it lags considerably inside and even when I exit those buildings. The only way I've gotten around this is saving, exiting to main menu and then reloading my save. But then I must keep doing this if I enter any building.

This has happened in all saves.

[Oskutin]

Can you upload your safe where this happens?

[sewer-dweller]

Obenseuer Save.zip