I experience blocking performance issues, especially when the weather effects are active:

The CPU usage suddenly jumps to 100% and the game freezes, more or less.

Over all game play also lags, but not that badly/

I tried to set it to Win 8 compatibility mode, tinkered with the power plan and used the Win Game Mode.

This is not a gaming laptop for sure, but given that the the game is not graphic intense at all, this is odd.

Any ideas how to avoid this?

Win 10
i7
8GB
SSD
Intel HD 4000 <- that's the problem, probably ...
DirectX 12